nvmem: u-boot-env: fix crc32 casting type

nvmem: u-boot-env: fix crc32 casting type

This fixes:
drivers/nvmem/u-boot-env.c:141:17: sparse: sparse: cast to restricted __le32

Fixes: d5542923f200 ("nvmem: add driver handling U-Boot environment variables")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220916122100.170016-14-srinivas.kandagatla@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>