msm: mhi_dev: Update msi_disable on fetching MSI config

Fix for the timing difference between host writing into MSI
capability register and MHI MMIO init where the first instance
of setting or resetting the msi_disable flag. Hence, updating
the msi_disable flag on fetching the MSI config from PCIe.
This will ensure to update the flag value in the case of EP
reading the MSI capability register before the host sets it.

Change-Id: I508a85e7107ee5a575fc03d54ab3e445049d73b2
Signed-off-by: Mohana Basava Tejesh Reddy Mareddy <quic_mmareddy@quicinc.com>