ARM: dts: msm: Use adsp heap for rfs_access on adsp

Add the phandle in the device tree to allow the
dma_alloc_coherrent call to use the adsp shared heap
when allocating the shared ram for the adsp rfs_access
clients.

Change-Id: I1c4e4aecf9b246828fa7d6e678c1c724cde4d273
Signed-off-by: Nikhilesh Reddy <reddyn@codeaurora.org>