USB_MUSB_HDRC depends on USB_GADGET_DUALSPEED.  If HDRC is selected
but DUALSPEED is not, the kernel oopses:

[    3.132781] Unable to handle kernel NULL pointer dereference at virtual address 00000000
[    3.141296] pgd = c0004000
[    3.144134] [00000000] *pgd=00000000
[    3.147918] Internal error: Oops: 5 [#1] SMP
[    3.152404] Modules linked in:
[    3.155609] CPU: 0    Not tainted  (3.1.0-rc9-wl+ #417)
[    3.161132] PC is at composite_setup+0x738/0xbb4
[    3.165985] LR is at vprintk+0x400/0x47c
[    3.170135] pc : [<c031df90>]    lr : [<c004c150>]    psr: 60000093
[    3.170135] sp : c065dd50  ip : dfb1f0fc  fp : c065ddbc
[    3.182220] r10: 00000000  r9 : df8fcae8  r8 : df8fcaa0
[    3.187713] r7 : 00000000  r6 : df8eaa20  r5 : dfae8ea0  r4 : 00000000
[    3.194580] r3 : df8fcae8  r2 : 00010002  r1 : c065dc40  r0 : 00000047
[    3.201446] Flags: nZCv  IRQs off  FIQs on  Mode SVC_32  ISA ARM  Segment kernel
[    3.209228] Control: 10c53c7d  Table: 8000404a  DAC: 00000015
[    3.215270] Process swapper (pid: 0, stack limit = 0xc065c2f8)
[    3.221405] Stack: (0xc065dd50 to 0xc065e000)
[...]
[    3.415405] [<c031df90>] (composite_setup+0x738/0xbb4) from [<c0310d18>] (musb_g_ep0_irq+0x9d0/0xaf8)
[    3.425109] [<c0310d18>] (musb_g_ep0_irq+0x9d0/0xaf8) from [<c030fb04>] (musb_interrupt+0xb48/0xc74)
[    3.434722] [<c030fb04>] (musb_interrupt+0xb48/0xc74) from [<c030fc98>] (generic_interrupt+0x68/0x80)
[    3.444458] [<c030fc98>] (generic_interrupt+0x68/0x80) from [<c0095204>] (handle_irq_event_percpu+0x9c/0x234)
[    3.454925] [<c0095204>] (handle_irq_event_percpu+0x9c/0x234) from [<c00953e8>] (handle_irq_event+0x4c/0x6c)
[    3.465270] [<c00953e8>] (handle_irq_event+0x4c/0x6c) from [<c0097e10>] (handle_fasteoi_irq+0xd8/0x110)
[    3.475158] [<c0097e10>] (handle_fasteoi_irq+0xd8/0x110) from [<c0094d2c>] (generic_handle_irq+0x34/0x3c)
[    3.485260] [<c0094d2c>] (generic_handle_irq+0x34/0x3c) from [<c0014ae4>] (handle_IRQ+0x88/0xc8)
[    3.494537] [<c0014ae4>] (handle_IRQ+0x88/0xc8) from [<c00085b0>] (asm_do_IRQ+0x18/0x1c)
[    3.503051] [<c00085b0>] (asm_do_IRQ+0x18/0x1c) from [<c0429e78>] (__irq_svc+0x38/0xc0)

This patch changes Kconfig so that USB_GADGET_DUALSPEED is selected
automatically by USB_MUSB_HDRC.
Signed-off-by: NLuciano Coelho <coelho@ti.com>
Signed-off-by: NFelipe Balbi <balbi@ti.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>