MIPS: ath79: simplify platform_get_resource_byname/devm_ioremap_resource

MIPS: ath79: simplify platform_get_resource_byname/devm_ioremap_resource

Remove unneeded error handling on the result of a call to
platform_get_resource_byname when the value is passed to devm_ioremap_resource.

A simplified version of the semantic patch that makes this change is as
follows: (http://coccinelle.lip6.fr/)

// <smpl>
@@
expression pdev,res,e,e1;
expression ret != 0;
identifier l;
@@

  res = platform_get_resource_byname(...);
- if (res == NULL) { ... \(goto l;\|return ret;\) }
  e = devm_ioremap_resource(e1, res);
// </smpl>

Signed-off-by: Julia Lawall <Julia.Lawall@lip6.fr>
Acked-by: Gabor Juhos <juhosg@openwrt.org>
Cc: kernel-janitors@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/5725/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>