selftests: rtc: rtctest: specify timeouts

uie_read is a commonly failing test that will block forever on buggy rtc
drivers. Shorten its timeout so it fails earlier. Also increase the timeout
for the two alarm test on a minute boundary.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>