drm: fix radeon DRM warnings when !CONFIG_DEBUG_FS

Compiling the radeon DRM driver with !CONFIG_DEBUG_FS
throws the following warnings:

drivers/gpu/drm/radeon/radeon_ttm.c: In function 'radeon_ttm_debugfs_init':
drivers/gpu/drm/radeon/radeon_ttm.c:714: warning: unused variable 'i'
drivers/gpu/drm/radeon/radeon_ttm.c: At top level:
drivers/gpu/drm/radeon/radeon_ttm.c:692: warning: 'radeon_mem_types_list' defined but not used
drivers/gpu/drm/radeon/radeon_ttm.c:693: warning: 'radeon_mem_types_names' defined but not used

Fix: move these variables inside the #if defined(CONFIG_DEBUG_FS)
block in radeon_ttm_debugsfs_init(), which is the only place using them.

Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Dave Airlie <airlied@linux.ie>