msm: scm: Add scm_call_noalloc and helper macros

Currently, scm_call internally calls kmalloc() to allocate a command
buffer structure. This prevents scm_call from working before kmalloc
structures are initialized or during atomic contexts. Allow clients
to pass in a pre-allocated buffer for scm_call to be used for internal
structures.

Change-Id: Id09500c8c696298228aefdcc2a61953e654677c9
CRs-Fixed: 498392
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>
init: Move stack canary initialization after setup_arch

Stack canary intialization involves getting a random number.
Getting this random number may involve accessing caches or other
architectural specific features which are not available until
after the architecture is setup. Move the stack canary initialization
later to accomodate this.

Change-Id: I00b564a2c3172229a44339c061fa380c17fe7d8e
CRs-Fixed: 498392
Signed-off-by: Laura Abbott <lauraa@codeaurora.org>