mmc: include linux/types.h for bool definition in atmel-mci.h

This patch adds an include of linux/types.h to make sure bool is defined
before utilized in this header file.

Signed-off-by: Hans-Christian Egtvedt <egtvedt@samfundet.no>
Acked-by: Ludovic Desroches <ludovic.desroches@atmel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>