linuxkpi: Define totalram_pages()

It returns `physmem`.

`__FreeBSD_version` is bumped to 1400080. We need that to remove a copy
of this function in the i915 DRM driver, maintained outside of base.

Reviewed by:	manu
Approved by:	manu
Differential Revision:	https://reviews.freebsd.org/D38531

sys/compat/linuxkpi/common/include/linux/mm.h

@@ -348,6 +348,12 @@ unlock_page(struct page *page)
 extern int is_vmalloc_addr(const void *addr);
 void si_meminfo(struct sysinfo *si);
 
+static inline unsigned long
+totalram_pages(void)
+{
+	return ((unsigned long)physmem);
+}
+
 #define	unmap_mapping_range(...)	lkpi_unmap_mapping_range(__VA_ARGS__)
 void lkpi_unmap_mapping_range(void *obj, loff_t const holebegin __unused,
     loff_t const holelen, int even_cows __unused);

sys/sys/param.h

@@ -76,7 +76,7 @@
  * cannot include sys/param.h and should only be updated here.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 1400079
+#define __FreeBSD_version 1400080
 
 /*
  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,