tpm: fix type of a local variable in tpm2_map_command()

The local variable 'handle' should have the type __be32 instead of u32.

Fixes: 745b361e ("tpm: infrastructure for TPM spaces")
Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>