MIPS: Loongson 1: more clk support and add select HAVE_CLK

This fixes a redefinition of clk_*:

arch/mips/loongson1/common/clock.c:23:13: error: redefinition of 'clk_get'
include/linux/clk.h:281:27: note: previous definition of 'clk_get' was here
arch/mips/loongson1/common/clock.c:41:15: error: redefinition of 'clk_get_rate'
include/linux/clk.h:302:29: note: previous definition of 'clk_get_rate' was here
make[3]: *** [arch/mips/loongson1/common/clock.o] Error 1

Signed-off-by: Yoichi Yuasa <yuasa@linux-mips.org>
Cc: linux-mips@linux-mips.org
Reviewed-by: John Crispin <blogic@openwrt.org>
Acked-by: Kelvin Cheung <keguang.zhang@gmail.com>
Patchwork: https://patchwork.linux-mips.org/patch/4143/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>