PcAtChipsetPkg: Define FixePCD's for RTC register values
PcAtChipsetPkg: Define FixePCD's for RTC register values

Define FixedPCD's to replace macros in RTC driver, to allow
for platform-specific configurations.

Cc: Ruiyu Ni <9fa3a6894a36bca79e6a72ad65af5a5702efecd1@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Leo Duran <de3438c1a4f7b527d4e4fd666d13484b4545c540@amd.com>
Reviewed-by: Ruiyu Ni <9fa3a6894a36bca79e6a72ad65af5a5702efecd1@intel.com>

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