video: fbdev: wm8505fb: add COMPILE_TEST support

Add COMPILE_TEST support to wm8505fb driver for better compile
testing coverage.

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/900c16b3-9306-7d17-f467-0f98bc95416a@samsung.com

drivers/video/fbdev/Kconfig

@@ -1639,7 +1639,7 @@ config FB_VT8500
 
 config FB_WM8505
 	bool "Wondermedia WM8xxx-series frame buffer support"
-	depends on (FB = y) && ARM && ARCH_VT8500
+	depends on (FB = y) && HAS_IOMEM && (ARCH_VT8500 || COMPILE_TEST)
 	select FB_SYS_FILLRECT if (!FB_WMT_GE_ROPS)
 	select FB_SYS_COPYAREA if (!FB_WMT_GE_ROPS)
 	select FB_SYS_IMAGEBLIT