MIPS: AR7: Fix redefinition of clk_* by adding select HAVE_CLK
arch/mips/ar7/clock.c:420:5: error: redefinition of 'clk_enable'
include/linux/clk.h:295:19: note: previous definition of 'clk_enable' was here
arch/mips/ar7/clock.c:426:6: error: redefinition of 'clk_disable'
include/linux/clk.h:300:20: note: previous definition of 'clk_disable' was here
arch/mips/ar7/clock.c:431:15: error: redefinition of 'clk_get_rate'
include/linux/clk.h:302:29: note: previous definition of 'clk_get_rate' was here
arch/mips/ar7/clock.c:437:13: error: redefinition of 'clk_get'
include/linux/clk.h:281:27: note: previous definition of 'clk_get' was here
arch/mips/ar7/clock.c:454:6: error: redefinition of 'clk_put'
include/linux/clk.h:291:20: note: previous definition of 'clk_put' was here
make[2]: *** [arch/mips/ar7/clock.o] Error 1