drivers/intel/gma: Allow SPARK function with side effects

Explicitly specifying the aspect `Side_Effects' is necessary for GCC
toolchains from 14.0 on. As older toolchains don't know the aspect,
we have to silence a warning about it, though.

Change-Id: I1eb879f57437587dc11d879fcc4042a70d384786
Signed-off-by: Nico Huber <[email protected]>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/80616
Reviewed-by: Felix Singer <[email protected]>
Reviewed-by: Thomas Heijligen <[email protected]>
Tested-by: build bot (Jenkins) <[email protected]>

Author: n-huber

gnat.adc

@@ -28,3 +28,7 @@ pragma Assertion_Policy
    Refined_Post         => Disable);
 pragma Overflow_Mode (General => Strict, Assertions => Eliminated);
 pragma SPARK_Mode (On);
+
+pragma Warnings
+  (GNAT, Off, """Side_Effects"" is not a valid aspect identifier",
+   Reason => """Side_Effects"" is new and needed for toolchain transition.");

src/drivers/intel/gma/gma.ads

@@ -11,6 +11,6 @@ package GMA is
       port     : in     Interfaces.C.int)
       return Interfaces.C.int
    with
-      Export, Convention => C, External_Name => "gma_read_edid";
+      Side_Effects, Export, Convention => C, External_Name => "gma_read_edid";
 
 end GMA;