This patch improves error reporting in the configuration parsing routines.
It also adds a few extra minor tweaks.

	#include linux/config.h and make the usual DEBUG settings
	available.

	Use the driver-model dev_xxx() macros for log output.

	Be much more explicit about the nature of errors, including
	configuration, interface, and altsetting numbers where
	appropriate.

	Log fatal problems as errors, non-fatal ones as warnings.

	Remove a #define'd constant that is already set in linux/usb.h.

	Fix some variables declared as pointer to char that really
	should be pointers to unsigned char.

	Replace a whole bunch of "out-of-memory" error messages with
	a single message.

	Wrap source lines that are longer than 80 columns (but not
	log output lines!).

	Clean up the logic for detecting errors when retrieving a
	configuration descriptor.

Apart from the log messages themselves, this introduces no functional
changes.