Using a signed variable as a parameter of FLASH_SNB() macro
generated "warning: The result of the left shift is undefined
because the left operand is negative"
Change-Id: I8b3fe840f9308962460906097df6ddd848c07b25
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: http://openocd.zylin.com/5356
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>