libpayload: Make Kconfig bools use IS_ENABLED()

This will make the code work with the different styles
of Kconfig (emit unset bools vs don't emit unset bools)

Roughly, the patch does this, and a little bit of fixing up:

perl -pi -e 's,ifdef (CONFIG_LP_.+?)\b,if IS_ENABLED\($1\),g' `find . -name *.[ch]`
perl -pi -e 's,ifndef (CONFIG_LP_.+?)\b,if !IS_ENABLED\($1\),g' `find . -name *.[ch]`

Change-Id: Ib8a839b056a1f806a8597052e1b571ea3d18a79f
Signed-off-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Reviewed-on: http://review.coreboot.org/10711
Tested-by: build bot (Jenkins)
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

payloads/libpayload/libcbfs/cbfs_core.c

@@ -121,7 +121,7 @@ struct cbfs_file *cbfs_get_file(struct cbfs_media *media, const char *name)
 
 	// TODO Add a "size" in CBFS header for a platform independent way to
 	// determine the end of CBFS data.
-#if defined(CONFIG_LP_ARCH_X86) && CONFIG_LP_ARCH_X86
+#if IS_ENABLED(CONFIG_LP_ARCH_X86)
 	// resolve actual length of ROM used for CBFS components
 	// the bootblock size was not taken into account
 	romsize -= ntohl(header->bootblocksize);