asm-generic: fix a compilation warning

asm-generic: fix a compilation warning

Fix this compilation warning on x86 by making flush_cache_vmap() inline.

  lib/ioremap.c: In function 'ioremap_page_range':
  lib/ioremap.c:214:16: warning: variable 'start' set but not used [-Wunused-but-set-variable]
    unsigned long start;
                  ^~~~~

While at it, convert all other similar functions to inline for
consistency.

Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Qian Cai <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>