target/ppc: code motion from translate_init.c.inc to gdbstub.c

target/ppc: code motion from translate_init.c.inc to gdbstub.c

All the code related to gdb has been moved from translate_init.c.inc
file to the gdbstub.c file, where it makes more sense.

Version 4 fixes the omission of internal.h in gdbstub, mentioned in
<[email protected]>, and the extra blank line.

Signed-off-by: Bruno Larsen (billionai) <[email protected]>
Suggested-by: Fabiano Rosas <[email protected]>
Message-Id: <20210426184706[email protected]>
Signed-off-by: David Gibson <[email protected]>