lib: Add a generic cmdline parse function parse_option_str

There should be a generic function to parse params like a=b,c
Adding parse_option_str in lib/cmdline.c which will return true
if there's specified option set in the params.

Also updated efi=old_map parsing code to use the new function

Signed-off-by: Dave Young <dyoung@redhat.com>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --cc arch/x86/platform/efi/efi.c
Simple merge

diff --cc include/linux/kernel.h
Simple merge

diff --cc lib/cmdline.c
Simple merge