Fix potential OOB write in btm_read_remote_ext_features_complete

Add event length check to avoid hci event sent from controller not
correct.
Add page number check to avoid page number is bigger than max page
number.

Bug: 141552859
Test: inject function
Merged-In: I3bd7349f382aa0e42123bbd835dcb60b77af099a
Change-Id: I3bd7349f382aa0e42123bbd835dcb60b77af099a