soc: qcom: smd: Remove use of VLAIS

Usage of VLAIS prevents clang from compiling this file, and it
also opens us to the possibility of allocating a large structure
on the stack to the point that we blow past the limit of the
kernel stack. Remove the VLAIS and allocate a structure on the
heap with kmalloc so that we're safer and more clang friendly.

Cc: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@sonymobile.com>
Signed-off-by: Andy Gross <agross@codeaurora.org>