powerpc: Use SWITCH_FRAME_SIZE for prom and rtas entry

[Michael Ellerman]

On Fri, 2018-10-12 at 02:44:06 UTC, Joel Stanley wrote:
> Commit 6c1719942e19 ("powerpc/of: Remove useless register save/restore
> when calling OF back") removed the saving of srr0 and srr1 when calling
> into OpenFirmware. Commit e31aa453bbc4 ("powerpc: Use LOAD_REG_IMMEDIATE
> only for constants on 64-bit") did the same for rtas.
> 
> This means we don't need to save the extra stack space and can use
> the common SWITCH_FRAME_SIZE.
> 
> There were already no users of _SRR0 and _SRR1 so we can remove them
> too.
> 
> Link: https://github.com/linuxppc/linux/issues/83
> Signed-off-by: Joel Stanley <joel at jms.id.au>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/ed9e84a4d703243a232e6549a13ded

cheers