Add support for calculating hashes with watchdog triggering

Implement watchodg-aware variants of hash calculation functions:
- crc32_wd()
- md5_wd()
- sha1_csum_wd()
The above functions calculate the hash of the input buffer in chunks,
triggering the watchdog after processing each chunk. The chunk size
is given as a function call parameter.

Signed-off-by: Bartlomiej Sieka <tur@semihalf.com>