PowerPC: Make test gdb.arch/powerpc-power10.exp Endian independent.

PowerPC: Make test gdb.arch/powerpc-power10.exp Endian independent.

The .quad statement stores the 64-bit hex value in Endian order.  When used
to store a 64-bit prefix instructions on Big Endian (BE) systems, the .quad
statement stores the 32-bit suffix followed by the 32-bit prefix rather
than the expected order of prefix word followed by the suffix word.  GDB
fetches 32-bits at a time when disassembling instructions.  The disassembly
on BE gets messed up since GDB fetches the suffix first and interprets it
as a word instruction not a prefixed instruction.  When gdb fetches the
prefix part of the instruction, following the initial suffix word, gdb
associates the prefix word incorrectly with the following 32-bits as the
suffix for the instruction when in fact it is the following instruction.

For example on BE we have two prefixed instructions stored using the
.quad statement as follows:

 addr    word                GDB action
---------------------------------------------
  1      suffix inst A   <- GDB interprets as a word instruction
  2      prefix inst A   <- GDB uses this prefix with

  3      suffix inst B   <- this suffix rather than the suffix at addr 1.
  4      prefix inst B

This patch changes the .quad statement into two .longs to explicitly store
the prefix followed by the suffix of the instruction.

The patch rearranges the instructions to put all of the word instructions
together followed by the prefix instructions for clarity.

The patch has been tested on Power 10 and Power 7 BE and LE to verify
the change works as expected.