drm/i915: [dinq] shut up two instances -Wunitialized

Introduced in commit 8461d22 and 8c59967

Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
[danvet: s/fix/shut up/ in the commit msg.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/i915/i915_gem.c

@@ -387,7 +387,7 @@ i915_gem_shmem_pread_slow(struct drm_device *dev,
 	char __user *user_data;
 	ssize_t remain;
 	loff_t offset;
-	int shmem_page_offset, page_length, ret;
+	int shmem_page_offset, page_length, ret = 0;
 	int obj_do_bit17_swizzling, page_do_bit17_swizzling;
 
 	user_data = (char __user *) (uintptr_t) args->data_ptr;
@@ -794,7 +794,7 @@ i915_gem_shmem_pwrite_slow(struct drm_device *dev,
 	ssize_t remain;
 	loff_t offset;
 	char __user *user_data;
-	int shmem_page_offset, page_length, ret;
+	int shmem_page_offset, page_length, ret = 0;
 	int obj_do_bit17_swizzling, page_do_bit17_swizzling;
 
 	user_data = (char __user *) (uintptr_t) args->data_ptr;