pmem: fix a name collision

Kernel test robot detected name collision when compiled on 'um'
architecture.  Rename "to_phys()"  to "pmem_to_phys()".

>> drivers/nvdimm/pmem.c:48:20: error: conflicting types for 'to_phys'; have 'phys_addr_t(struct pmem_device *, phys_addr_t)' {aka 'long long unsigned int(struct pmem_device *, long long unsigned int)'}
      48 | static phys_addr_t to_phys(struct pmem_device *pmem, phys_addr_t offset)
         |                    ^~~~~~~
   In file included from arch/um/include/asm/page.h:98,
                    from arch/um/include/asm/thread_info.h:15,
                    from include/linux/thread_info.h:60,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/um/include/generated/asm/preempt.h:1,

   arch/um/include/shared/mem.h:12:29: note: previous definition of 'to_phys' with type 'long unsigned int(void *)'
      12 | static inline unsigned long to_phys(void *virt)
         |                             ^~~~~~~

vim +48 drivers/nvdimm/pmem.c
    47
  > 48	static phys_addr_t to_phys(struct pmem_device *pmem, phys_addr_t offset)
    49	{
    50		return pmem->phys_addr + offset;
    51	}
    52

Fixes: 9409c9b6 (pmem: refactor pmem_clear_poison())
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jane Chu <jane.chu@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20220630182802.3250449-1-jane.chu@oracle.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/pmem.c

@@ -45,7 +45,7 @@ static struct nd_region *to_region(struct pmem_device *pmem)
 	return to_nd_region(to_dev(pmem)->parent);
 }
 
-static phys_addr_t to_phys(struct pmem_device *pmem, phys_addr_t offset)
+static phys_addr_t pmem_to_phys(struct pmem_device *pmem, phys_addr_t offset)
 {
 	return pmem->phys_addr + offset;
 }
@@ -63,7 +63,7 @@ static phys_addr_t to_offset(struct pmem_device *pmem, sector_t sector)
 static void pmem_mkpage_present(struct pmem_device *pmem, phys_addr_t offset,
 		unsigned int len)
 {
-	phys_addr_t phys = to_phys(pmem, offset);
+	phys_addr_t phys = pmem_to_phys(pmem, offset);
 	unsigned long pfn_start, pfn_end, pfn;
 
 	/* only pmem in the linear map supports HWPoison */
@@ -97,7 +97,7 @@ static void pmem_clear_bb(struct pmem_device *pmem, sector_t sector, long blks)
 static long __pmem_clear_poison(struct pmem_device *pmem,
 		phys_addr_t offset, unsigned int len)
 {
-	phys_addr_t phys = to_phys(pmem, offset);
+	phys_addr_t phys = pmem_to_phys(pmem, offset);
 	long cleared = nvdimm_clear_poison(to_dev(pmem), phys, len);
 
 	if (cleared > 0) {