meson: update default options for libdrm

Libdrm now uses enabled/disabled/auto for the drivers, migrate to these
new defaults.

Error message from meson:

  wlroots| subprojects/wlroots/subprojects/libdrm/meson.build:21:0: Exception: Value "false" (of type "string") for combo option "Enable support for Intel's KMS API." is not one of the choices. Possible choices are (as string): "enabled", "disabled", "auto".`

meson.build

@@ -110,20 +110,20 @@ drm = dependency('libdrm',
 	version: '>=2.4.113',
 	fallback: 'libdrm',
 	default_options: [
-		'intel=false',
-		'radeon=false',
-		'amdgpu=false',
-		'nouveau=false',
-		'vmwgfx=false',
-		'omap=false',
-		'exynos=false',
-		'freedreno=false',
-		'tegra=false',
-		'vc4=false',
-		'etnaviv=false',
-		'cairo-tests=false',
-		'man-pages=false',
-		'valgrind=false',
+		'intel=disabled',
+		'radeon=disabled',
+		'amdgpu=disabled',
+		'nouveau=disabled',
+		'vmwgfx=disabled',
+		'omap=disabled',
+		'exynos=disabled',
+		'freedreno=disabled',
+		'tegra=disabled',
+		'vc4=disabled',
+		'etnaviv=disabled',
+		'cairo-tests=disabled',
+		'man-pages=disabled',
+		'valgrind=disabled',
 		'tests=false',
 	],
 )