bus: mhi: host: pci_generic: Update EDL firmware path for Foxconn modems

Foxconn uses a unique firmware for their MHI based modems. So the generic
firmware from Qcom won't work. Hence, update the EDL firmware path to
include the 'foxconn' subdirectory based on the modem SoC so that the
Foxconn specific firmware could be used.

Respective firmware will be upstreamed to linux-firmware repo.

Cc: stable@vger.kernel.org # 6.11
Fixes: bf30a75e ("bus: mhi: host: Add support for Foxconn SDX72 modems")
Signed-off-by: Slark Xiao <slark_xiao@163.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/20240725022941.65948-1-slark_xiao@163.com


[mani: Reworded the subject and description]
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>