soc: marvell: hw_access: add dependency OCTEONTX2_AF

commit 58861e6a30bd6f16a5979950efac1d345b655bd3 from
git@git.assembla.com:cavium/WindRiver.linux.git

hw_access call functions in octoentx2_af driver, and it
is compiled as module by default. So need to add this
dependency since compile will fail on other platforms without
OCTEONTX2_AF being enabled.

Signed-off-by: Jia Ma <jiam@marvell.com>
Change-Id: Ib12113dd7535b71a556c23403c1c7c0904724f9a
Reviewed-on: https://sj1git1.cavium.com/c/IP/SW/kernel/linux/+/56019
Tested-by: Jia Ma <Jia.Ma@cavium.com>
Reviewed-by: Jia Ma <Jia.Ma@cavium.com>
Signed-off-by: Ruiqiang Hao <Ruiqiang.Hao@windriver.com>