target-arm: Fix AArch32:AArch64 general-purpose register mapping

target-arm: Fix AArch32:AArch64 general-purpose register mapping

There is an error in functions aarch64_sync_32_to_64() and
aarch64_sync_64_to_32() with mapping of registers between AArch32 and
AArch64.  This commit fixes the mapping to match the v8 ARM ARM
section D1.20.1 (table D1-77).

Signed-off-by: Sergey Sorokin <[email protected]>
Message-id: 1440796451[email protected]
Reviewed-by: Peter Maydell <[email protected]>
[PMM: tidied commit message a bit]
Signed-off-by: Peter Maydell <[email protected]>