rtcwake: remove RTC_ALM_READ and RTC_ALM_SET compatibility

rtcwake: remove RTC_ALM_READ and RTC_ALM_SET compatibility

The RTC_WKALM_RD and RTC_WKALM_SET have been available since 2.6.17, and
preferred way since 2007.  Keeping the fallbacks to the old interface is
no longer needed.

Reference: https://github.com/torvalds/linux/commit/e824290e5dcfaf2120da587b16d10dfdff8d5d3e
Reference: https://github.com/torvalds/linux/commit/f8245c26886c912627ebc49f714e4491261224c4
Reviewed-by: Benno Schulenberg <bensberg@justemail.net>
Signed-off-by: Sami Kerola <kerolasa@iki.fi>