BLE Host - Fix default ble_hs configuration.
BLE Host - Fix default ble_hs configuration.

This commit includes the following changes:

* Set default max_l2cap_chans to: (3 * max_connections).  This is
  exactly the number of required channels, and is the only logical value
  to use since we don't support connection-oriented channels yet.  Prior
  to this change, this setting was arbitrarily set to 16.

* Set all default GATT server resource counts to 0.  The expectation is
  that these values will be increased as appropriate as GATT services
  are initialized.

* Reduce some overly-ambitious numbers to defaults that are more
  realistic:

      o max_gattc_procs:        16 --> 4
      o max_l2cap_sig_procs:    8  --> 1

X-Original-Commit: db3c76b3293d05b8b1ad8380384e49e6daf0eea1

apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble,apache/mynewt-nimble