nfit, nd_blk: BLK status register is only 32 bits

Only read 32 bits for the BLK status register in read_blk_stat().

The format and size of this register is defined in the
"NVDIMM Driver Writer's guide":

http://pmem.io/documents/NVDIMM_Driver_Writers_Guide.pdfSigned-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Reported-by: Nicholas Moulin <nicholas.w.moulin@linux.intel.com>
Tested-by: Nicholas Moulin <nicholas.w.moulin@linux.intel.com>
Reviewed-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/acpi/nfit.c

@@ -1024,7 +1024,7 @@ static void wmb_blk(struct nfit_blk *nfit_blk)
 		wmb_pmem();
 }
 
-static u64 read_blk_stat(struct nfit_blk *nfit_blk, unsigned int bw)
+static u32 read_blk_stat(struct nfit_blk *nfit_blk, unsigned int bw)
 {
 	struct nfit_blk_mmio *mmio = &nfit_blk->mmio[DCR];
 	u64 offset = nfit_blk->stat_offset + mmio->size * bw;
@@ -1032,7 +1032,7 @@ static u64 read_blk_stat(struct nfit_blk *nfit_blk, unsigned int bw)
 	if (mmio->num_lines)
 		offset = to_interleave_offset(offset, mmio);
 
-	return readq(mmio->base + offset);
+	return readl(mmio->base + offset);
 }
 
 static void write_blk_ctl(struct nfit_blk *nfit_blk, unsigned int bw,