remoteproc: qcom_q6v5_mss: Add modem support on MSM8226

Add support for the external power block headswitch register needed by
MSM8226 and some other qcom platforms.

Co-developed-by: Matti Lehtimäki <matti.lehtimaki@gmail.com>
Signed-off-by: Matti Lehtimäki <matti.lehtimaki@gmail.com>
Reviewed-by: Stephan Gerhold <stephan.gerhold@linaro.org>
Signed-off-by: Luca Weiss <luca@lucaweiss.eu>
Link: https://lore.kernel.org/r/20250217-msm8226-modem-v5-5-2bc74b80e0ae@lucaweiss.eu


Signed-off-by: Bjorn Andersson <andersson@kernel.org>