For strings and integers, the config_is_xxx macros are useless and
sometimes misleading:

  #define CONFIG_INITRAMFS_SOURCE ""
  #define config_is_initramfs_source() 1

Cc: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Signed-off-by: NMichal Marek <mmarek@suse.cz>