firmware: qcom: scm: Simplify set_cold/warm_boot_addr()

The qcom_scm_set_cold/warm_boot_addr() implementations have a lot of
functionality that is actually not used.

For example, set_warm_boot_addr() caches the last used entry address
and skips making the SCM call when the entry address is unchanged.
But there is actually just a single call of qcom_scm_set_warm_boot_addr()
in the whole kernel tree, which always configures the entry address
to cpu_resume_arm().

Simplify this by having a single qcom_scm_set_boot_addr() function
for both cold and warm boot address. This is totally sufficient for
the functionality supported in the mainline tree.

Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211201130505.257379-3-stephan@gerhold.net