firmware: qcom_scm: Mark string array const

Mark the qcom_scm_convention_names[] array const as it isn't changed.

Cc: Elliot Berman <eberman@codeaurora.org>
Fixes: 9a434cee ("firmware: qcom_scm: Dynamically support SMCCC and legacy conventions")
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20210222031431.3831189-1-swboyd@chromium.org


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