msm: pcie: scale PCIe resources based on Gen speed after link is up

After PCIe link is up, scale PCIe resources based on the Gen
speed rather than the value of CX vote for the Gen speed. Before
CX vote was the only factor for scaling resources. This is an
incorrect assumption as additional resources can be added and
do not have any dependency with CX. Therefore, remove the
dependency on CX and bind it to the Gen speed instead.

Change-Id: I64ca90892769e43d694a21e172f51d7fd4c76e68
Signed-off-by: Tony Truong <truong@codeaurora.org>