clk: qcom: msm8916: Fix return value check in qcom_apcs_msm8916_clk_probe()

clk: qcom: msm8916: Fix return value check in qcom_apcs_msm8916_clk_probe()

BugLink: http://bugs.launchpad.net/bugs/1763040
In case of error, the function dev_get_regmap() returns NULL pointer
not ERR_PTR(). The IS_ERR() test in the return value check should be
replaced with NULL test.

Fixes: 81ac38847a1d ("clk: qcom: Add APCS clock controller support")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>
(cherry picked from commit 55c19eee3b471e7ca7e38783836f7b7137c9d14f)
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Acked-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>