mesa: drop -Dgallium-opencl flag

The Clover support has been deprecated upstream and got explicitly
disabled by the 0001-dont-build-clover-frontend.patch patch. Drop it
from the build flags.

(From OE-Core rev: ba712aabaa7cb20e97dd9e97456357a0ed24337e)

Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-graphics/mesa/mesa.inc

@@ -145,11 +145,7 @@ PACKAGECONFIG[egl] = "-Degl=enabled, -Degl=disabled"
 
 # "opencl" also requires libclc and gallium-llvm to be present in PKGCONFIG!
 # Be sure to enable them both for the target and for the native build.
-PACKAGECONFIG[opencl] = " \
-    -Dgallium-opencl=icd -Dgallium-rusticl=true, \
-    -Dgallium-opencl=disabled -Dgallium-rusticl=false, \
-    bindgen-cli-native \
-"
+PACKAGECONFIG[opencl] = "-Dgallium-rusticl=true, -Dgallium-rusticl=false, bindgen-cli-native"
 
 PACKAGECONFIG[broadcom] = ""
 PACKAGECONFIG[etnaviv] = ",,python3-pycparser-native"