uboot-imx

usb: common: Use a global definition for 'min3'

We can use a common global method for calculating minimum of
3 numbers. Put the same in 'common header' and let 'ehci'
use it.

Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
Acked-by: Tom Rini <trini@ti.com>