firmware: qcom: scm: add a missing forward declaration for struct device

We reference struct device in the private scm header but we neither
include linux/device.h nor forward declare it. Fix it.
Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
Reviewed-by: Andrew Halaney <ahalaney@redhat.com>
Tested-by: Andrew Halaney <ahalaney@redhat.com> # sc8280xp-lenovo-thinkpad-x13s
Link: https://lore.kernel.org/r/20231017092732.19983-3-brgl@bgdev.plSigned-off-by: Bjorn Andersson <andersson@kernel.org>

drivers/firmware/qcom/qcom_scm.h

@@ -4,6 +4,8 @@
 #ifndef __QCOM_SCM_INT_H
 #define __QCOM_SCM_INT_H
 
+struct device;
+
 enum qcom_scm_convention {
 	SMC_CONVENTION_UNKNOWN,
 	SMC_CONVENTION_LEGACY,