msm: Add support for early random numbers

Currently, the software random number generator is not initialized
until relatively late in the boot process. Software that relies on
random numbers early will not be reliable. Entropy sources are
available early but not early enough for some use cases which means
that moving the software random number generation earlier is not an
option. Instead we initialize the random pool with values from a
HW RNG accessed through a call to the secure environment.

Change-Id: Id756a8740df7ec938984c3e7de22681e0270bb5b
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
[ohaugan@codeaurora.org: Removed unsupported scm api]
Signed-off-by: Olav Haugan <ohaugan@codeaurora.org>