soc: qcom: icc-bwmon: remove redundant ret variable

Return value from devm_regmap_field_bulk_alloc() directly
instead of taking this in another redundant variable.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Jinpeng Cui <cui.jinpeng2@zte.com.cn>
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20220823133620.211902-1-cui.jinpeng2@zte.com.cn