tty: serial: pmac_zilog: Remove unused disposable variable 'garbage'

Fixes the following W=1 kernel build warning(s):

drivers/tty/serial/pmac_zilog.h:365:58: warning: variable ‘garbage’ set but not used [-Wunused-but-set-variable]

Cc: Greg Kroah-Hartman <[e-mail]>
Cc: Jiri Slaby <[e-mail]>
Cc: Michael Ellerman <[e-mail]>
Cc: Benjamin Herrenschmidt <[e-mail]>
Cc: Paul Mackerras <[e-mail]>
Cc: [e-mail]
Cc: [e-mail]
Signed-off-by: Lee Jones <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/tty/serial/pmac_zilog.h

···
 
 /* Misc macros */
 #define ZS_CLEARERR(port)    (write_zsreg(port, 0, ERR_RES))
-#define ZS_CLEARFIFO(port)   do { volatile unsigned char garbage; \
-				     garbage = read_zsdata(port); \
-				     garbage = read_zsdata(port); \
-				     garbage = read_zsdata(port); \
+#define ZS_CLEARFIFO(port)   do {                       \
+				     read_zsdata(port); \
+				     read_zsdata(port); \
+				     read_zsdata(port); \
 				} while(0)
 
 #define ZS_IS_CONS(UP)			((UP)->flags & PMACZILOG_FLAG_IS_CONS)