of_pci_irq: kill useless variable in of_irq_parse_pci()

The 'lspec' variable only caused pointless promotions from u8 to u32 on each
loop iteration, while it's enough to promote only once, after the loop.

Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
Signed-off-by: Grant Likely <grant.likely@linaro.org>