Staging: fsl-mc: include: mc: Kernel type 's16' preferred over 'int16_t'

Follow the kernel type preferrences of using 's16' over 'int16_t'.

Signed-off-by: Shiva Kerdel <shiva@exdev.nl>
Acked-by: Stuart Yoder <stuart.yoder@nxp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>