contrib/elf2dmp: fix code style

Originally elf2dmp were added with some code style issues,
especially in pe.h header, and some were introduced by
2d0fc797. Fix them now.

Signed-off-by: Viktor Prutyanov <viktor@daynix.com>
Reviewed-by: Annie Li <annie.li@oracle.com>
Message-id: 20230222211246.883679-2-viktor@daynix.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>