ARM: prima2: always enable reset controller

The atlas7 clock controller driver registers a reset controller
for itself, which causes a link error when the subsystem is
disabled:

drivers/built-in.o: In function `atlas7_clk_init':
drivers/clk/sirf/clk-atlas7.c:1681: undefined reference to `reset_controller_register'

As the clk driver does not have a Kconfig symbol for itself
but it always built-in when the platform is enabled, we have
to ensure that the reset controller subsystem is also built-in
in this case.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
Fixes: 301c5d29 ("clk: sirf: add CSR atlas7 clk and reset support")