linux-postmarketos-mediatek-mt6735: V=1 workaround (MR 5240)

Until this kernel is upgraded to 6.2, we need V=1 to work around silent
make output leading to failing builds.

device/testing/linux-postmarketos-mediatek-mt6735/APKBUILD

@@ -31,8 +31,9 @@ prepare() {
 
 build() {
 	unset LDFLAGS
+	# V=1: workaround for pma#1990
 	make ARCH="$_carch" CC="${CC:-gcc}" \
-		KBUILD_BUILD_VERSION=$((pkgrel + 1 ))
+		KBUILD_BUILD_VERSION=$((pkgrel + 1 )) V=1
 }
 
 package() {