usb: bdc: Fix an error handling path in 'bdc_probe()' when no suitable DMA config is available

If no suitable DMA configuration is available, a previous 'bdc_phy_init()'
call must be undone by a corresponding 'bdc_phy_exit()' call.

Branch to the existing error handling path instead of returning
directly.

Fixes: cc29d4f6

 ("usb: bdc: Add support for USB phy")
Acked-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/0c5910979f39225d5d8fe68c9ab1c147c68ddee1.1629314734.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>