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