Kconfig: Add dependency on HASH to verified boot

Building with verified boot support requires hash, add that
dependency here. Otherwise the following build error will come out
without crc command.

      LD      u-boot
lib/built-in.o: In function `hash_calculate':
lib/rsa/rsa-checksum.c:29: undefined reference to
`hash_progressive_lookup_algo'
...
make[1]: *** [u-boot] Error 1

Signed-off-by: Kelvin Cheung <keguang.zhang@gmail.com>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>