usb: musb: rename ->reset() to ->recover()

recover is a much better name than reset, considering
we don't really reset the IP, just run platform-specific
babble recovery algorithm.

while at that, also fix a typo in comment and add kdoc
for recover memeber of platform_ops.

Tested-by: Bin Liu <b-liu@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>