SPM: Use SPMLOG_ERRMSG instead of ERROR_MSG macro

The ERROR_MSG() macro is still used through the code
although is not defined anymore. Use the SPMLOG_ERRMSG
macro instead to provide error message prints.

Signed-off-by: Antonio de Angelis <antonio.deangelis@arm.com>
Change-Id: If23455e6f008b0ecc471579591c5d1e2e95cdccb