ARM: pass 'struct reg *' to register r/w routines

Implementations need to access the register struct they modify;
make it easier and less error-prone to identify the instance.
(This removes over 10% of the ARMV4_5_CORE_REG_MODE nastiness...)

Plus some minor fixes noted when making these updates:  ARM7/ARM9
accessor methods should be static; don't leave CPSR wrongly marked
"dirty"; note significant XScale omissions in register handling;
and have armv4_5_build_reg_cache() record its result.

Rename "struct armv4_5_core_reg" as "struct arm_reg"; it's used
for more than those older architecture generations.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>

src/target/arm9tdmi.c

@@ -754,7 +754,6 @@ static void arm9tdmi_build_reg_cache(struct target *target)
 	struct armv4_5_common_s *armv4_5 = target_to_armv4_5(target);
 
 	(*cache_p) = armv4_5_build_reg_cache(target, armv4_5);
-	armv4_5->core_cache = (*cache_p);
 }
 
 int arm9tdmi_init_target(struct command_context *cmd_ctx,