usb: common: usb-conn-gpio: Don't log an error on probe deferral

This patch makes the printout of the error message for failing to get a
VBUS regulator handle conditional on the error code being something other
than -EPROBE_DEFER.

Deferral is a normal thing, we don't need an error message for this.

Cc: Chunfeng Yun <chunfeng.yun@mediatek.com>
Cc: Nagarjuna Kristam <nkristam@nvidia.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-usb@vger.kernel.org
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20191128134358.3880498-2-bryan.odonoghue@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>