MIPS: MSP71xx: request_irq() failure ignored in msp_pcibios_config_access()

Produce an error if request_irq() fails.

Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: "Ithamar R. Adema" <ithamar.adema@team-embedded.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>