pinctrl: meson: Drop unused aml_pctl_find_group_by_name()

pinctrl: meson: Drop unused aml_pctl_find_group_by_name()

aml_pctl_find_group_by_name() is not used anywhere, as reported by W=1
clang build:

  pinctrl-amlogic-a4.c:600:2: error: unused function 'aml_pctl_find_group_by_name' [-Werror,-Wunused-function]

Fixes: 6e9be3abb78c ("pinctrl: Add driver support for Amlogic SoCs")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Xianwei Zhao <xianwei.zhao@amlogic.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Link: https://lore.kernel.org/20250509150114.299962-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>