slimbus: qcom: fix incompatible pointer warning

One of the pointer passed to dmam_alloc_coherent seems to be
phys_addr_t * instead of dma_addr_t *. This address will be
used by dma apis, so change this to proper type.

Reported-by: kbuild test robot <fengguang.wu@intel.com>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>