firmware: qcom_scm: remove IS_ERR() checks from qcom_scm_bw_{en,dis}able()

Since the qcom_scm_probe() function returns with an error if
__scm->path contains an error pointer, it is not needed to
verify that again in the qcom_scm_bw_{en,dis}able() functions
so remove the superfluous IS_ERR() checks.

Signed-off-by: Gabor Juhos <j4g8y7@gmail.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Link: https://lore.kernel.org/r/20240308-qcom_scm-is_err-check-v1-1-9c3e1ceefafe@gmail.com


Signed-off-by: Bjorn Andersson <andersson@kernel.org>