USB: phy: remove custom DBG macro

Use the in-kernel pr_debug() calls instead of trying to roll your own
DBG macro.  This means the dynamic debugging calls now work here, and
there is no dependency on CONFIG_USB_DEBUG for the phy code anymore.

Acked-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>