The amount of console output is controlled by the LOG_LEVEL build
option. Using tf_printf without any #ifdef depending on the LOG_LEVEL
doesn't give the user that flexibility.

This patch replaces all occurrences of tf_printf that prints error, but
aren't dependent on LOG_LEVEL, with the ERROR macro.

Change-Id: Ib5147f14fc1579398a11f19ddd0e840ff6692831
Signed-off-by: Antonio Nino Diaz <antonio.ninodiaz@arm.com>