The MIPS BMC63XX subarch does not provide/support clk_set_parent().
This causes build errors in a few drivers, so add a simple implementation
of that function so that callers of it will build without errors.
Fixes these build errors:
ERROR: modpost: "clk_set_parent" [sound/soc/jz4740/snd-soc-jz4740-i2s.ko] undefined!
ERROR: modpost: "clk_set_parent" [sound/soc/atmel/snd-soc-atmel-i2s.ko] undefined!
Fixes: e7300d04bd08 ("MIPS: BCM63xx: Add support for the Broadcom BCM63xx family of SOCs." )
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>