PowerPC Exception warnings

[Chris Johns]

Hello,

The mvme2703 BSP is producing warnings for these lines of code:

https://git.rtems.org/rtems/tree/bsps/powerpc/shared/exceptions/ppc_exc.S#n132
https://git.rtems.org/rtems/tree/bsps/powerpc/shared/exceptions/ppc_exc.S#n135

The warnings is:

../../../bsps/powerpc/shared/exceptions/ppc_exc.S:132: Warning: invalid register
expression
../../../bsps/powerpc/shared/exceptions/ppc_exc.S:135: Warning: invalid register
expression

The code is:

	/* ppc405 has a critical exception using srr2/srr3 */
	WRAP	_FLVR=p405_crit _PRI=crit _SRR0=srr2 _SRR1=srr3 _RFI=rfci

	/* bookE has critical exception using csrr0 cssr1 */
	WRAP	_FLVR=bookE_crit _PRI=crit _SRR0=csrr0 _SRR1=csrr1 _RFI=rfci

I do not have enough PowerPC foo to fix this.

Chris