bus: mhi: pci_generic: Introduce quectel EM1XXGR-L support

bus: mhi: pci_generic: Introduce quectel EM1XXGR-L support

Add support for EM1XXGR-L modems, this modem series is based on SDX24
qcom chip. The modem is mainly based on MBIM protocol for both the
data and control path. The drivers for these channels (mhi-net-mbim and
mhi_uci) are not yet part of the kernel but will be integrated by
different series.

Signed-off-by: Loic Poulain <loic.poulain@linaro.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1614971808-22156-2-git-send-email-loic.poulain@linaro.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>