rtc: Fix naming of RTC symbols

These symbols have the same name as the symbols from lib QMSI, which
causes a compilation failure, when lib QMSI is used.

This replaces the offending symbols with names which are more consistent
with the rest of the file (rtc_ prefix).

Change-Id: I288a1a229bf0b40f3b6fc8ffb35c502f998054b8
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>