The function parse_platform_config in firmware.c calls crc32_le.
Building without CRC32 selected causes a link error:

drivers/built-in.o: In function `parse_platform_config':
(.text+0x92ffa): undefined reference to `crc32_le'
Signed-off-by: Markus Böhme <markus.boehme@mailbox.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>