tests: drivers: can: api: support numaker_m2l31ki

Add support for Nuvoton numaker board numaker_m2l31ki.
m2l31x has 4 MPU regions and can't afford one more region
for USERSPACE, so set CONFIG_USERSPACE=n in m2l31ki_defconfig.

Signed-off-by: cyliang tw <cyliang@nuvoton.com>