CHROMIUM: Add #line to arm_mpu.c

Work around coreboot GCC preprocessor bug.

BUG=b:272518464
TEST=BOARD=brya ; zmake build --coverage $BOARD &&
./util/find_non_exec_lines.py build/zephyr/$BOARD/output/zephyr.info

Change-Id: I606cd552eb141967c8a6c3e4609da00340d884f5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5926409
Tested-by: Jeremy Bettis <jbettis@chromium.org>
Reviewed-by: Tomasz Michalec <tmichalec@google.com>
Commit-Queue: Tomasz Michalec <tmichalec@google.com>
Auto-Submit: Jeremy Bettis <jbettis@chromium.org>

arch/arm/core/mpu/arm_mpu.c

@@ -67,6 +67,7 @@ static uint8_t static_regions_num;
 #error "Unsupported ARM CPU"
 #endif
 
+#line 71
 static int region_allocate_and_init(const uint8_t index,
 	const struct arm_mpu_region *region_conf)
 {