efi_selftest: print CRC32 of initrd as hexadecimal

Print the CRC32 loaded via the EFI_LOAD_FILE2_PROTOCOL as a hexadecimal
number.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>