bus: mhi: host: Add a separate timeout parameter for waiting ready

Some devices(eg. SDX75) take longer than expected (default, 8 seconds) to
set ready after reboot. Hence add optional ready timeout parameter and pass
the appropriate timeout value to mhi_poll_reg_field() to wait enough for
device ready as part of power up sequence.

Signed-off-by: Qiang Yu <quic_qianyu@quicinc.com>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1699344890-87076-2-git-send-email-quic_qianyu@quicinc.com
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>