stand: Fix brand positioning on framebuffer console

The drawer.lua script ignores the values in loader_brand_x and
loader_brand_y on framebuffer consoles, always positioning the brand at
(1, 1).

Allow it to be positioned by accepting the x and y values just like the
text version.  For example:

/boot/lua/gfx-nanobsd.lua:

    return {
    	brand = {
    		graphic = {
    			""
    		},
    		requires_color = true,
    		image = "/boot/images/freebsd-logo-rev.png"
    	}
    }

/boot/loader.conf.d/bootloader.conf:

    loader_logo="none"
    loader_brand="nanobsd"
    loader_brand_x="15"

PR:		255202
Reviewed by:	manu, imp
Approved by:	emaste (mentor)
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D49092

(cherry picked from commit 7d1d7f4230)

stand/lua/drawer.lua

@@ -327,7 +327,7 @@ local function drawbrand()
 	if core.isFramebufferConsole() and
 	    gfx.term_putimage ~= nil and
 	    branddef.image ~= nil then
-		if gfx.term_putimage(branddef.image, 1, 1, 0, 7, 0)
+		if gfx.term_putimage(branddef.image, x, y, 0, 7, 0)
 		then
 			return true
 		end