usb: gadget: goku_udc: Remove uses of seq_<foo> return values

The seq_printf/seq_puts/seq_putc return values, because they
are frequently misused, will eventually be converted to void.

See: commit 1f33c41c ("seq_file: Rename seq_overflow() to
     seq_has_overflowed() and make public")

Miscellanea:

o Coalesce formats, realign arguments
o Create static functions for statement expression macros
o Use c90 style comments instead of c99

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>