Fix -Wextra warnings from GCC 11

(cherry picked from commit 6bdd84b8d5a8671d0a574739b27a1ddbdfa88e1e)

drivers/gles2/rasterizer_gles2.cpp

@@ -358,7 +358,7 @@ void RasterizerGLES2::set_boot_image(const Ref<Image> &p_image, const Color &p_c
 	canvas->canvas_begin();
 
 	RID texture = storage->texture_create();
-	storage->texture_allocate(texture, p_image->get_width(), p_image->get_height(), 0, p_image->get_format(), VS::TEXTURE_TYPE_2D, p_use_filter ? VS::TEXTURE_FLAG_FILTER : 0);
+	storage->texture_allocate(texture, p_image->get_width(), p_image->get_height(), 0, p_image->get_format(), VS::TEXTURE_TYPE_2D, p_use_filter ? (uint32_t)VS::TEXTURE_FLAG_FILTER : 0);
 	storage->texture_set_data(texture, p_image);
 
 	Rect2 imgrect(0, 0, p_image->get_width(), p_image->get_height());

drivers/gles3/rasterizer_gles3.cpp

@@ -294,7 +294,7 @@ void RasterizerGLES3::set_boot_image(const Ref<Image> &p_image, const Color &p_c
 	canvas->canvas_begin();
 
 	RID texture = storage->texture_create();
-	storage->texture_allocate(texture, p_image->get_width(), p_image->get_height(), 0, p_image->get_format(), VS::TEXTURE_TYPE_2D, p_use_filter ? VS::TEXTURE_FLAG_FILTER : 0);
+	storage->texture_allocate(texture, p_image->get_width(), p_image->get_height(), 0, p_image->get_format(), VS::TEXTURE_TYPE_2D, p_use_filter ? (uint32_t)VS::TEXTURE_FLAG_FILTER : 0);
 	storage->texture_set_data(texture, p_image);
 
 	Rect2 imgrect(0, 0, p_image->get_width(), p_image->get_height());