cmd: smccc: Print results in hex instead of dec

Printing return value in HEX instead of DEC. Return values are 64 bit
values which impossible to decode in DEC. For example getting CHIP ID in
dec is quite long.

Signed-off-by: Michal Simek <michal.simek@amd.com>
Link: https://lore.kernel.org/r/9a0278a7da729cb69b7a4d46c5e7eb8c3217c635.1676450712.git.michal.simek@amd.com