ion: msm: Fix several errors in the MSM ION kernel header

ION clients that reside in the kernel may need information that is
present in the UAPI header, such as flags to specify memory
attributes, or IDs to allocate from different heaps, so include
the UAPI header in the kernel space header. Also, ensure that
drivers that use this header can still compile even when
CONFIG_ION_MSM_HEAPS is not set.

Change-Id: If030a58ce62b73b66b337b6dfc6a607bbc0ce193
Signed-off-by: Isaac J. Manjarres <isaacm@codeaurora.org>