powerpc/signal32: Reorder user reads in restore_tm_user_regs()

In restore_tm_user_regs(), regroup the reads from 'sr' and the ones
from 'tm_sr' together in order to allow two block user accesses
in following patch.

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7c518b9a4c8e5ae9a3bfb647bc8b20bf820233af.1616151715.git.christophe.leroy@csgroup.eu