irqchip/renesas-irqc: Remove error messages on out-of-memory conditions

There is no need to print error messages if kzalloc() or
ioremap_nocache() fail, as the memory allocation core already takes care
of that.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>