sunxi: enable MUSB in A53 subtarget

sunxi: enable MUSB in A53 subtarget

The Pine64(+) and the SoPine64 baseboard has two USB ports. One of
these (the lower) is connected directly to a USB host, the other
one's (upper) PHY is shared with the separate OTG controller. In
order to get it working, MUSB support needs to be enabled.

As there are other targets which compile MUSB support into the kernel
and not package it into modules, the same is done here.

[    1.348760] usb usb5: New USB device found, idVendor=1d6b, idProduct=0002, bcdDevice= 5.04
[    1.357029] usb usb5: New USB device strings: Mfr=3, Product=2, SerialNumber=1
[    1.364250] usb usb5: Product: MUSB HDRC host driver
[    1.369219] usb usb5: Manufacturer: Linux 5.4.99 musb-hcd
[    1.374617] usb usb5: SerialNumber: musb-hdrc.1.auto
[    1.379891] hub 5-0:1.0: USB hub found
[    1.383677] hub 5-0:1.0: 1 port detected
[...]
[  697.299440] usb 1-1: new high-speed USB device number 2 using ehci-platform
[  697.461855] usb 1-1: New USB device found, idVendor=090c, idProduct=1000, bcdDevice=11.00
[  697.470038] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  697.477180] usb 1-1: Product: USB Flash Disk

Signed-off-by: Zoltan HERPAI <wigyori@uid0.hu>