remoteproc: Drop redundant REMOTEPROC dependency from driver Kconfigs

All the remoteproc platform driver Kconfig symbols are defined and
included under an if REMOTEPROC condition, so the dependency on
REMOTEPROC is implicit and they do not need an explicit 'depends
on REMOTEPROC' line. So, clean these up.

Signed-off-by: Suman Anna <s-anna@ti.com>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>