IntelFrameworkModulePkg/IsaSerialDxe: Use PcdSerialClockRate instead of hard code value

So that the driver can work on a certain hardware when a platform module
dynamically changes the PCD value.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Ruiyu Ni <ruiyu.ni@intel.com>
Cc: Feng Tian <feng.tian@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@17607 6f19259b-4bc3-4df7-8a09-765794883524
3 files changed