monitor: fix dead assignment spotted by clang

Value stored to 'nb_per_line' is never read.
Signed-off-by: NBlue Swirl <blauwirbel@gmail.com>

monitor.c

@@ -1109,7 +1109,7 @@ static void memory_dump(Monitor *mon, int count, int format, int wsize,
                         target_phys_addr_t addr, int is_physical)
 {
     CPUState *env;
-    int nb_per_line, l, line_size, i, max_digits, len;
+    int l, line_size, i, max_digits, len;
     uint8_t buf[16];
     uint64_t v;
 
@@ -1148,7 +1148,6 @@ static void memory_dump(Monitor *mon, int count, int format, int wsize,
         line_size = 8;
     else
         line_size = 16;
-    nb_per_line = line_size / wsize;
     max_digits = 0;
 
     switch(format) {