Staging: speakup: Add identifier name to function declaration arguments.

void (*read_buff_add) argument didn't have an identifier name,
adding a name to it like the rest of all functions' arguments.

Signed-off-by: Sam Muhammed <[e-mail]>
Reviewed-by: Samuel Thibault <[e-mail]>
Link: https://lore.kernel.org/r/b[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/speakup/spk_types.h

···
 	void (*flush)(struct spk_synth *synth);
 	int (*is_alive)(struct spk_synth *synth);
 	int (*synth_adjust)(struct st_var_header *var);
-	void (*read_buff_add)(u_char);
+	void (*read_buff_add)(u_char c);
 	unsigned char (*get_index)(struct spk_synth *synth);
 	struct synth_indexing indexing;
 	int alive;