accel/ivpu: Change test_mode module param to bitmask

Change meaning of test_mode module parameter from integer value
to bitmask allowing setting different test features with corresponding
bits.

Signed-off-by: Karol Wachowski <karol.wachowski@linux.intel.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Signed-off-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231028133415.1169975-7-stanislaw.gruszka@linux.intel.com