uboot-imx

pfuze: Fix unsigned variable for less-than-zero comparison

According to the Coverity result, a unsigned int variable is used fo less-
than-zero comparison, the result is never true. Need to fix the variable
type to signed int.

Signed-off-by: Ye.Li <B37916@freescale.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>
Cc: Przemyslaw Marczak <p.marczak@samsung.com>
Cc: Stefano Babic <sbabic@denx.de>
Reviewed-by: Stefano Babic <sbabic@denx.de>