ath79: mikrotik: enable 2nd USB on RouterBOARD 922UAGS-5HPacD

ath79: mikrotik: enable 2nd USB on RouterBOARD 922UAGS-5HPacD

RB922 boards have 2 separate USB controllers:
- 1 is connected to Slot Type A
- 1 is connected to the mini PCIe port

Enable the 2nd one too.

Before:

[    5.339304] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI)
Driver
[    5.355053] SCSI subsystem initialized
[    5.364184] ehci-fsl: Freescale EHCI Host controller driver
[    5.372377] ehci-platform: EHCI generic platform driver
[    5.378053] ehci-platform 1b000000.usb: EHCI Host Controller
[    5.383861] ehci-platform 1b000000.usb: new USB bus registered,
assigned bus number 1
[    5.391932] ehci-platform 1b000000.usb: irq 14, io mem 0x1b000000
[    5.410730] ehci-platform 1b000000.usb: USB 2.0 started, EHCI 1.00
[    5.417739] hub 1-0:1.0: USB hub found
[    5.422280] hub 1-0:1.0: 1 port detected
[    5.434007] usbcore: registered new interface driver usb-storage

After:

[    5.342988] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI)
Driver
[    5.358687] SCSI subsystem initialized
[    5.367813] ehci-fsl: Freescale EHCI Host controller driver
[    5.375998] ehci-platform: EHCI generic platform driver
[    5.381695] ehci-platform 1b000000.usb: EHCI Host Controller
[    5.387507] ehci-platform 1b000000.usb: new USB bus registered,
assigned bus number 1
[    5.395571] ehci-platform 1b000000.usb: irq 14, io mem 0x1b000000
[    5.416050] ehci-platform 1b000000.usb: USB 2.0 started, EHCI 1.00
[    5.423089] hub 1-0:1.0: USB hub found
[    5.427578] hub 1-0:1.0: 1 port detected
[    5.432432] ehci-platform 1b400000.usb: EHCI Host Controller
[    5.438254] ehci-platform 1b400000.usb: new USB bus registered,
assigned bus number 2
[    5.446325] ehci-platform 1b400000.usb: irq 15, io mem 0x1b400000
[    5.468049] ehci-platform 1b400000.usb: USB 2.0 started, EHCI 1.00
[    5.475082] hub 2-0:1.0: USB hub found
[    5.479574] hub 2-0:1.0: 1 port detected
[    5.491305] usbcore: registered new interface driver usb-storage

Fixes: 8f93c05a59 ("ath79: add support for MikroTik RouterBOARD
922UAGS-5HPacD")
Signed-off-by: Koen Vandeputte <koen.vandeputte@citymesh.com>