proc: unify mem_read() and mem_write()

proc: unify mem_read() and mem_write()

commit 572d34b946bae070debd42db1143034d9687e13f upstream.

No functional changes, cleanup and preparation.

mem_read() and mem_write() are very similar. Move this code into the
new common helper, mem_rw(), which takes the additional "int write"
argument.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit b49767a65a6454f7d546068a785e25dbb0eabbcd)
For Oracle bug 13811116

Signed-off-by: Chuck Anderson <chuck.anderson@oracle.com>