fbdev: wm8505fb: Use devm_platform_ioremap_resource()

According to commit 7945f929 ("drivers: provide
devm_platform_ioremap_resource()"), convert platform_get_resource(),
devm_ioremap_resource() to a single call to Use
devm_platform_ioremap_resource(), as this is exactly what this function
does.

Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Helge Deller <deller@gmx.de>