PCI: pcie, aer: remove spinlock in aerdrv_errprint.c

The static buffer errmsg_buff[] is used only for building error
message in fixed format, and is protected by a spinlock.

This patch removes this buffer and the spinlock.

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Reviewed-by: Andrew Patterson <andrew.patterson@hp.com>
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>