msm: rpm: Stub out RPM APIs when CONFIG_MSM_RPM[_SMD] is undefined

To allow common code across targets that use
the legacy RPM APIs and the new RPM SMD APIs, stub
out RPM and RPM resources APIs when CONFIG_MSM_RPM
or CONFIG_MSM_RPM_SMD is undefined.

Change-Id: I6ce8b23b4535c5f2e65912bdb65483ed355f40ad
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>