clk: keystone: fix compile testing

clk: keystone: fix compile testing

[ Upstream commit b276445e98fe28609688fb85b89a81b803910e63 ]

Some keystone clock drivers can be selected when COMPILE_TEST is
enabled but since commit b745c0794e2f ("clk: keystone: Add sci-clk
driver support") they are never actually built.

Enable compile testing by allowing the build system to process the
keystone drivers.

Fixes: b745c0794e2f ("clk: keystone: Add sci-clk driver support")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>