powerpc/mpc5200: move lpbfifo node and fix its interrupt property

The LPB FIFO interrupt is a peripheral interrupt, thus its L1 cell
has to be 2 instead of 3. Fix it and while at it, move the lpbfifo
node to the common dtsi file.

This patch fixes the irqdomain warning:
 ...
 WARNING: at kernel/irq/irqdomain.c:766
 Modules linked in:
 NIP: c00587fc LR: c0058e0c CTR: c0014e54
 REGS: c7837c10 TRAP: 0700   Tainted: G        W     (3.7.0-rc1-00003-g6e51414)
 MSR: 00029032 <EE,ME,IR,DR,RI>  CR: 82cd8322  XER: 00000000
 TASK = c7834000[1] 'swapper' THREAD: c7836000
 GPR00: 00000001 c7837cc0 c7834000 c7806080 000000d7 c7837d20 00000003 c7837cec
 GPR08: c7837ce8 00000000 00000000 00000008 82cd3342 00000000 c0003f88 00000000
 GPR16: 00000000 00000000 00000000 00000000 00000000 00000000 00000000 c7850ec0
 GPR24: c782b010 00000000 00000001 c7852900 00000003 c7df5be0 c7806080 000000d7
 NIP [c00587fc] irq_linear_revmap+0x2c/0x4c
 LR [c0058e0c] irq_create_mapping+0x28/0x124

Reported-by: Stefan Roese <sr@denx.de>
Signed-off-by: Anatolij Gustschin <agust@denx.de>