Fix the path to sdk_car_x86_64.mk

Although sdk_car_x86_64.mk was recently relocated, in
sdk_car_md_x86_64.mk, the old path to sdk_car_x86_64.mk is still
referenced.

Fix: 266644499
Test: build sdk_car_md_x86_64-userdebug
Merged-In: I36a0b05c2de500d7a7caa03d3c7e4dcddda409ea
Change-Id: Ia075073902eb316359bdaad2f1c73b75d4eef02f
1 file changed