msm: sps: Make DESC_FULL_ADDR(flags, addr) provide a phys_addr_t result

By convention, both the 'flags' and 'addr' arguments passed to
DESC_FULL_ADDR() come from struct sps_iovec, and so neither of
these values are 64 bit types. To guarantee that the result of
DESC_FULL_ADDR() is large enough to contain at 64bit address,
add an explicit phys_addr_t cast inside the macro.

Change-Id: Ie1f0ba15448e4386761e60ea22251ceca246d86a
Signed-off-by: Matt Wagantall <mattw@codeaurora.org>