staging: rtl8188eu: Fix spelling

rtl8188eu contains some spelling errors in comment lines as well as in
constants. Harmless as they are, they still make the code feel a bit
unclean, which is not something we want in the kernel.

Improve this by fixing typos so they won't catch eyes of future driver
developers anymore.

Signed-off-by: Wolfgang Hartmann <wolfgang.hartmann@siemens.com>
Signed-off-by: Manish Shrestha <manishshrestha2006@gmail.com>
Signed-off-by: Valentine Sinitsyn <valentine.sinitsyn@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>