char: tpm: Add missing error check for devm_kzalloc

Currently these driver are missing a check on the return value of devm_kzalloc,
which would cause a NULL pointer dereference in a OOM situation.

This patch adds a missing check for tpm_i2c_atmel.c and tpm_i2c_nuvoton.c

Cc: stable@vger.kernel.org
Signed-off-by: Kiran Padwal <kiran.padwal@smartplayin.com>
Reviewed-By: Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
Signed-off-by: Peter Huewe <peterhuewe@gmx.de>