dwc_otg: Call usb_hcd_unlink_urb_from_ep with lock held in completion handler

usb_hcd_unlink_urb_from_ep must be called with the HCD lock held.  Calling it
asynchronously in the tasklet was not safe (regression in
c4564d4a1a0a9b10d4419e48239f5d99e88d2667).

This change unlinks it from the endpoint prior to queueing it for handling in
the tasklet, and also adds a check to ensure the urb is OK to be unlinked
before doing so.

NULL pointer dereference kernel oopses had been observed in usb_hcd_giveback_urb
when a USB device was unplugged/replugged during data transfer.  This effect
was reproduced using automated USB port power control, hundreds of replug
events were performed during active transfers to confirm that the problem was
eliminated.
Speed up console framebuffer imageblit function

Especially on platforms with a slower CPU but a relatively high
framebuffer fill bandwidth, like current ARM devices, the existing
console monochrome imageblit function used to draw console text is
suboptimal for common pixel depths such as 16bpp and 32bpp. The existing
code is quite general and can deal with several pixel depths. By creating
special case functions for 16bpp and 32bpp, by far the most common pixel
formats used on modern systems, a significant speed-up is attained
which can be readily felt on ARM-based devices like the Raspberry Pi
and the Allwinner platform, but should help any platform using the
fb layer.

The special case functions allow constant folding, eliminating a number
of instructions including divide operations, and allow the use of an
unrolled loop, eliminating instructions with a variable shift size,
reducing source memory access instructions, and eliminating excessive
branching. These unrolled loops also allow much better code optimization
by the C compiler. The code that selects which optimized variant is used
is also simplified, eliminating integer divide instructions.

The speed-up, measured by timing 'cat file.txt' in the console, varies
between 40% and 70%, when testing on the Raspberry Pi and Allwinner
ARM-based platforms, depending on font size and the pixel depth, with
the greater benefit for 32bpp.

Signed-off-by: Harm Hanemaaijer <fgenfb@yahoo.com>
Merge pull request #314 from hglm/cfbimageblit

Speed up framebuffer console text rendering
Merge pull request #312 from wmdb/rpi-3.6.y

dwc_otg: Call usb_hcd_unlink_urb_from_ep with lock held in completion ta...