[rsyslog.j2] fix typo in VAR_LOG_SIZE_KB (sonic-net#9954)

This issue causes negative threshold value and thus deleting log files even when there is enough space.

This issue causes negative threshold value and thus deleting log files even when there is enough space.

- Why I did it
To fix an issue when log files get deleted even if there is enough space.

- How I did it
Fixed an typo.

- How to verify it
Run the portion of the script that calculates threshold, see that the threshold is calculated correctly.

Signed-off-by: Stepan Blyschak <stepanb@nvidia.com>

files/image_config/logrotate/rsyslog.j2

@@ -57,7 +57,7 @@
         # should be disabled, just in case they get created and rotated
         RESERVED_SPACE_KB=4096
 
-        VARL_LOG_SIZE_KB={{var_log_kb}}
+        VAR_LOG_SIZE_KB={{var_log_kb}}
 
         # Limit usable space to 90% of the partition minus the reserved space for other logs
         USABLE_SPACE_KB=$(( (VAR_LOG_SIZE_KB * 90 / 100) - RESERVED_SPACE_KB))