tracing/eprobes: Have event probes be consistent with kprobes and uprobes

In the Linux kernel, the following vulnerability has been resolved:

tracing/eprobes: Have event probes be consistent with kprobes and uprobes

Currently, if a symbol "@" is attempted to be used with an event probe

(eprobes), it will cause a NULL pointer dereference crash.

Both kprobes and uprobes can reference data other than the main registers.

Such as immediate address, symbols and the current task name. Have eprobes

do the same thing.

For "comm", if "comm" is used and the event being attached to does not

have the "comm" field, then make it the "$comm" that kprobes has. This is

consistent to the way histograms and filters work.