sim: Fix some -Werror=shadow=compatible-local issues in aarch64/simulator.c
With GCC 14 -Werror=shadow=compatible-local flags the reuse of single
capital letters used in aarch64/cpustate.h enums
88 | expand_logical_immediate (uint32_t S, uint32_t R, uint32_t N)
| ~~~~~~~~~^
In file included from ../../binutils-gdb/sim/aarch64/aarch64-sim.h:27,
from ../../binutils-gdb/sim/aarch64/simulator.c:33:
217 | N = 1 << N_IDX
| ^
sim/aarch64/simulator.c: In function ‘expand_logical_immediate’:
sim/aarch64/simulator.c:88:60: error: declaration of ‘N’ shadows a previous local [-Werror=shadow=compatible-local]
sim/aarch64/cpustate.h:217:3: note: shadowed declaration is here
1 file changed
