arm64: dts: qcom: pmk8550: Correct gpio node name

arm64: dts: qcom: pmk8550: Correct gpio node name

The reg for the GPIOs is 0xb800 and not 0x8800, so fix this copy-paste
mistake.

Fixes: e9c0a4e48489 ("arm64: dts: qcom: Add PMK8550 pmic dtsi")
Signed-off-by: Luca Weiss <luca.weiss@fairphone.com>
Reviewed-by: Konrad Dybcio <konrad.dybcio@oss.qualcomm.com>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://lore.kernel.org/r/20250625-pmk8550-gpio-name-v1-1-58402849f365@fairphone.com
Signed-off-by: Bjorn Andersson <andersson@kernel.org>