parisc: eisa: Fix infinite loop when parsing invalid IRQ value

When an invalid value is passed via the "eisa_irq_edge=" kernel
command line parameter (e.g. "eisa_irq_edge=16,5"), eisa_irq_setup()
prints an error message and continues without advancing the current
position.  As a result the same invalid value is parsed again and
again, causing an infinite loop while the kernel boots.

Advance to the next comma-separated entry, or stop parsing when there
is no next entry, before continuing so that the remaining entries are
processed normally.

Signed-off-by: Pei Xiao <xiaopei01@kylinos.cn>
Cc: stable@vger.kernel.org
Signed-off-by: Helge Deller <deller@gmx.de>