target-arm: fix incorrect temporary variable freeing

tmp4 and tmp5 temporary variables are allocated using tcg_const_i32
but incorrectly released using dead_tmp which will cause resource
leak tracking to report false leaks.

Signed-off-by: Juha Riihimäki <juha.riihimaki@nokia.com>
Acked-by:  Laurent Desnogues <laurent.desnogues@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
