The Modem Subsystem clock provider have a bunch of generic properties
that are needed in a device tree. Add a YAML schemas for those.

Add clock ids for GCC MSS and MSS clocks which are required to bring
the modem out of reset.
Signed-off-by: Taniya Das <tdas@codeaurora.org>
Link: https://lkml.kernel.org/r/1584596131-22741-2-git-send-email-tdas@codeaurora.orgReviewed-by: Rob Herring <robh@kernel.org>
Tested-by: Sibi Sankar <sibis@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>