x86, libnvdimm, pmem: remove global pmem api

Now that all callers of the pmem api have been converted to dax helpers that
call back to the pmem driver, we can remove include/linux/pmem.h and
asm/pmem.h.

Cc: <x86@kernel.org>
Cc: Jeff Moyer <jmoyer@redhat.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Toshi Kani <toshi.kani@hpe.com>
Cc: Oliver O'Halloran <oohall@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

drivers/nvdimm/pmem.h

@@ -6,9 +6,11 @@
 #include <linux/fs.h>
 
 #ifdef CONFIG_ARCH_HAS_PMEM_API
+#define ARCH_MEMREMAP_PMEM MEMREMAP_WB
 void arch_wb_cache_pmem(void *addr, size_t size);
 void arch_invalidate_pmem(void *addr, size_t size);
 #else
+#define ARCH_MEMREMAP_PMEM MEMREMAP_WT
 static inline void arch_wb_cache_pmem(void *addr, size_t size)
 {
 }