[Bugfix][Coredump] Fix coredump_enable() in envsetup.sh

-P means PID to affect (default $PPID), while -p means Pipe buffer (512 bytes), we should use -P here.

Bug: 234049197

Test: Perform ". build/envsetup.sh" in host, then run "coredump_enable $PID".

Change-Id: Id373f2a7adc56d6a40720ec900b2561c9dbea2b1