selftests/powerpc: Add more SPR numbers, TM & VMX instructions to 'reg.h'/'instructions.h'

This patch adds SPR number for TAR, PPR, DSCR special
purpose registers. It also adds TM, VSX, VMX related
instructions which will then be used by patches later
in the series.

Now that the new DSCR register definitions (SPRN_DSCR_PRIV and
SPRN_DSCR) are defined outside this directory, use them instead.

Signed-off-by: Anshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: Simon Guo <wei.guo.simon@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>