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