libertas: kill SendSinglePacket() function.

Make a start on reducing the number of pointless nested functions,
starting with the StudlyCaps. No semantic changes (yet) -- we can sort
out the now-obvious discrepancy in the failure paths in a separate
commit.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>