arm: Add missing test name prefix for pl031 and spinlock

pl031 and spinlock testcase without prefix, when running
the unit tests in TAP mode (./run_tests.sh -t), it is
difficult to the test results.

The test results：
ok 13 - Periph/PCell IDs match
ok 14 - R/O fields are R/O
ok 15 - RTC ticks at 1HZ
ok 16 - RTC IRQ not pending yet
...
ok 24 -   RTC IRQ not pending anymore
ok 25 - CPU1: Done - Errors: 0
ok 26 - CPU0: Done - Errors: 0

It should be like this：
ok 13 - pl031: Periph/PCell IDs match
ok 14 - pl031: R/O fields are R/O
ok 15 - pl031: RTC ticks at 1HZ
ok 16 - pl031: RTC IRQ not pending yet
...
ok 24 - pl031:   RTC IRQ not pending anymore
ok 25 - spinlock: CPU0: Done - Errors: 0
ok 26 - spinlock: CPU1: Done - Errors: 0

Signed-off-by: Chen Qun <kuhn.chenqun@huawei.com>
Signed-off-by: Andrew Jones <drjones@redhat.com>