ShellPkg: Improve "ping" output by adding equals sign after time

The output of the "ping" command shows the time without a space between
the label and the value. e.g.:

20 bytes from 192.168.0.1 : icmp_seq=1 ttl=1 time1~2ms

Improve the readability and consistency by adding an equals sign for the
time value:

20 bytes from 192.168.0.1 : icmp_seq=1 ttl=1 time=1~2ms

Signed-off-by: Rebecca Cran <rebecca@quicinc.com>
Reviewed-by: Zhichao Gao <zhichao.gao@intel.com>