USB: xhci - fix math in xhci_get_endpoint_interval()
USB: xhci - fix math in xhci_get_endpoint_interval()

When parsing exponent-expressed intervals we subtract 1 from the
value and then expect it to match with original + 1, which is
highly unlikely, and we end with frequent spew:

	usb 3-4: ep 0x83 - rounding interval to 512 microframes

Also, parsing interval for fullspeed isochronous endpoints was
incorrect - according to USB spec they use exponent-based
intervals (but xHCI spec claims frame-based intervals). I trust
USB spec more, especially since USB core agrees with it.

This should be queued for stable kernels back to 2.6.31.

Reviewed-by: Micah Elizabeth Scott <45b9372d3d6883e588eb18cca37878d6aa2d5cd5@vmware.com>
Signed-off-by: Dmitry Torokhov <10a8c465cefc9bdd6c925e26964d23c90f1141cc@vmware.com>
Signed-off-by: Sarah Sharp <d4c4fc5069677be84f589aa6e14eedffef9ba12f@linux.intel.com>
Cc: 4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@kernel.org

KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs