Hexagon: Make pfn accessors statics inlines

Making virt_to_pfn() a static inline taking a strongly typed
(const void *) makes the contract of a passing a pointer of that
type to the function explicit and exposes any misuse of the
macro virt_to_pfn() acting polymorphic and accepting many types
such as (void *), (unitptr_t) or (unsigned long) as arguments
without warnings.

For symmetry do the same with pfn_to_virt().

For compiletime resolution of __pa() we need PAGE_OFFSET which
was not available to __pa() and resolved by the preprocessor
wherever __pa() was used. Fix this by explicitly including
<asm/mem-layout.h> where required, following the pattern of the
architectures page.h file.
Acked-by: Brian Cain <bcain@quicinc.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/hexagon/include/asm/page.h

@@ -78,6 +78,9 @@ typedef struct page *pgtable_t;
 #define __pgd(x)       ((pgd_t) { (x) })
 #define __pgprot(x)    ((pgprot_t) { (x) })
 
+/* Needed for PAGE_OFFSET used in the macro right below */
+#include <asm/mem-layout.h>
+
 /*
  * We need a __pa and a __va routine for kernel space.
  * MIPS says they're only used during mem_init.
@@ -125,8 +128,16 @@ static inline void clear_page(void *page)
  */
 #define page_to_phys(page)      (page_to_pfn(page) << PAGE_SHIFT)
 
-#define virt_to_pfn(kaddr)      (__pa(kaddr) >> PAGE_SHIFT)
-#define pfn_to_virt(pfn)        __va((pfn) << PAGE_SHIFT)
+static inline unsigned long virt_to_pfn(const void *kaddr)
+{
+	return __pa(kaddr) >> PAGE_SHIFT;
+}
+
+static inline void *pfn_to_virt(unsigned long pfn)
+{
+	return (void *)((unsigned long)__va(pfn) << PAGE_SHIFT);
+}
+
 
 #define page_to_virt(page)	__va(page_to_phys(page))