Staging: rtl8192e: Remove unnecessary macro

This patch removes the RTLLIB_PRINT_STR macro definition because it's
only defined in the header and it's never referenced. It also removes
PRINTABLE and MAX_STR_LEN, which were defined as helpers for the first
one.

Signed-off-by: Cristina Opriceana <cristina.opriceana@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>