scripts/kallsyms.c Make the comment up-to-date with current implementation

The comment in scripts/kallsyms.c describing the usage of
scripts/kallsyms does not reflect the latest implementation.
Fix the comment to be equivalent to what the usage() function prints.

Signed-off-by: Yuma Ueda <cyan@0x00a1e9.dev>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org>
Link: https://lore.kernel.org/r/20221118133631.4554-1-cyan@0x00a1e9.dev
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>