hvc_console: Allow backends to set I/O buffer size

To allow HVC backends to set the I/O buffer sizes to values
that are most efficient for the backend, change the macro
definitions where the buffer sizes are set to be conditional
on whether or not the macros are already defined.  Also,
rename the macros from N_OUTBUF to HVC_N_OUBUF and from

Typical usage in the backend source file would be:

 #define HVC_N_OUTBUF 32
 #define HVC_N_INBUF 32
 #include "hvc_console.h"

Signed-off-by: Geoff Levand <geoff@infradead.org>
1 file changed