usb: dwc2: Fix IN FIFO allocation

usb: dwc2: Fix IN FIFO allocation

On chips with fewer FIFOs than endpoints (for example RK3288 which has 9
endpoints, but only 6 which are cabable of input), the DPTXFSIZN
registers above the FIFO count may return invalid values.

With logging added on startup, I see:

	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=1 sz=256
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=2 sz=128
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=3 sz=128
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=4 sz=64
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=5 sz=64
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=6 sz=32
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=7 sz=0
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=8 sz=0
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=9 sz=0
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=10 sz=0
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=11 sz=0
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=12 sz=0
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=13 sz=0
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=14 sz=0
	dwc2 ff580000.usb: dwc2_hsotg_init_fifo: ep=15 sz=0

but:

	# cat /sys/kernel/debug/ff580000.usb/fifo
	Non-periodic FIFOs:
	RXFIFO: Size 275
	NPTXFIFO: Size 16, Start 0x00000113

	Periodic TXFIFOs:
		DPTXFIFO 1: Size 256, Start 0x00000123
		DPTXFIFO 2: Size 128, Start 0x00000223
		DPTXFIFO 3: Size 128, Start 0x000002a3
		DPTXFIFO 4: Size 64, Start 0x00000323
		DPTXFIFO 5: Size 64, Start 0x00000363
		DPTXFIFO 6: Size 32, Start 0x000003a3
		DPTXFIFO 7: Size 0, Start 0x000003e3
		DPTXFIFO 8: Size 0, Start 0x000003a3
		DPTXFIFO 9: Size 256, Start 0x00000123

so it seems that FIFO 9 is mirroring FIFO 1.

Fix the allocation by using the FIFO count instead of the endpoint count
when selecting a FIFO for an endpoint.

Acked-by: Minas Harutyunyan <hminas@synopsys.com>
Signed-off-by: John Keeping <john@metanate.com>
Signed-off-by: Felipe Balbi <balbi@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>