plugins/syscall: Added a table-like summary output

plugins/syscall: Added a table-like summary output

Added a table-like output which contains the total number of calls
for each used syscall along with the number of errors that occurred.

Per-call tracing is still available through supplying the argument
``print`` to the plugin.

Signed-off-by: Mahmoud Mandour <ma.mandourr@gmail.com>
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20210519032409.3041-1-ma.mandourr@gmail.com>
Message-Id: <20210520174303.12310-9-alex.bennee@linaro.org>