SurfaceFlinger: fix invalid PhysicalDisplayId in onConfigChanged event

A conversion error (uint64_t -> uint32_t) was causing a trunction
of displayId value which lead to invalid displayId in onConfigChanged.

Test: adb shell /data/nativetest64/libsurfaceflinger_unittest/libsurfaceflinger_unittest
Bug: 129159940
Change-Id: I9d24cac0b9e74c7b20421d2b7d9fd65c16cca9e1