target/hppa: Drop diag_getshadowregs_pa2 and diag_putshadowregs_pa2

target/hppa: Drop diag_getshadowregs_pa2 and diag_putshadowregs_pa2

diag_getshadowregs_pa2() and diag_putshadowregs_pa2() were added in
commit 3bdf20819e68 based on some analysis of ODE code, but now they
conflict with the generic mfdiag/mtdiag instructions. I believe the
former analysis was wrong, so remove them again. Note that all diag
instructions are badly documented, so most things are based on reverse
engineering and thus may be wrong.

Signed-off-by: Helge Deller <deller@gmx.de>
Fixes: 3bdf20819e68 ("target/hppa: Add diag instructions to set/restore shadow registers")
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>