libdrm/intel: Explain dependency on xorg in Kconfig only for BR2_i386/BR2_x86_64

Suggested by Yann: http://article.gmane.org/gmane.comp.lib.uclibc.buildroot/82731

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

package/libdrm/Config.in

@@ -27,6 +27,7 @@ config BR2_PACKAGE_LIBDRM_INTEL
 	  installs intel graphics driver
 
 comment "libdrm intel driver depends on X.org"
+	depends on BR2_i386 || BR2_x86_64
 	depends on !BR2_PACKAGE_XORG7
 
 config BR2_PACKAGE_LIBDRM_RADEON