ARM: SAMSUNG: Should check for IS_ERR(clk) instead of NULL

commit a5d8f4765f0e92ef027492a8cb979c5b8d45f2c3 upstream.

On the error condition clk_get() returns ERR_PTR().

Signed-off-by: Jonghwan Choi <jhbird.choi@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>