staging: imx-drm: use true and false for bool variables

This patch fixes coccinelle errors for bool variables
initialized with 1 or 0 instead of true and false.

Signed-off-by: Valentina Manea <valentina.manea.m@gmail.com>
Reviewed-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>