ARM: msm: Remove MSM_SCM

Commit 8fc1b0f8 ("ARM: qcom: Split Qualcomm support into legacy and
multiplatform") removed all users of Kconfig symbol MSM_SCM. Remove that
symbol too.

Signed-off-by: Paul Bolle <pebolle@tiscali.nl>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>