powerpc: Sort and de-dup primary opcodes in ppc-opcode.h

Some of the primary opcodes are duplicated. Remove those, and sort the
rest of the primary opcodes to make it easy to read.

Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a05edf638a2638d708fc2db0272f6317837b5eab.1648648712.git.naveen.n.rao@linux.vnet.ibm.com