selftests: ftrace: Use "grep -E" instead of "egrep"

The latest version of grep claims the egrep is now obsolete so the build
now contains warnings that look like:
	egrep: warning: egrep is obsolescent; using grep -E
fix this up by moving the related file to use "grep -E" instead.

  sed -i "s/egrep/grep -E/g" `grep egrep -rwl tools/testing/selftests/ftrace`

Here are the steps to install the latest grep:

  wget http://ftp.gnu.org/gnu/grep/grep-3.8.tar.gz
  tar xf grep-3.8.tar.gz
  cd grep-3.8 && ./configure && make
  sudo make install
  export PATH=/usr/local/bin:$PATH
Signed-off-by: Tiezhu Yang <yangtiezhu@loongson.cn>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/selftests/ftrace/test.d/preemptirq/irqsoff_tracer.tc

@@ -46,10 +46,10 @@ cat trace
 grep -q "tracer: preemptoff" trace || fail
 
 # Check the end of the section
-egrep -q "5.....us : <stack trace>" trace || fail
+grep -E -q "5.....us : <stack trace>" trace || fail
 
 # Check for 500ms of latency
-egrep -q "latency: 5..... us" trace || fail
+grep -E -q "latency: 5..... us" trace || fail
 
 reset_tracer
 
@@ -69,10 +69,10 @@ cat trace
 grep -q "tracer: irqsoff" trace || fail
 
 # Check the end of the section
-egrep -q "5.....us : <stack trace>" trace || fail
+grep -E -q "5.....us : <stack trace>" trace || fail
 
 # Check for 500ms of latency
-egrep -q "latency: 5..... us" trace || fail
+grep -E -q "latency: 5..... us" trace || fail
 
 reset_tracer
 exit 0