video: xilinxfb: replace devm_request_and_ioremap by devm_ioremap_resource

Use devm_ioremap_resource instead of devm_request_and_ioremap.

This was done using the semantic patch
scripts/coccinelle/api/devm_ioremap_resource.cocci

The initialization of drvdata->regs_phys was manually moved lower, to take
advantage of the NULL test on res performed by devm_ioremap_resource.

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>