kernel: bump to 4.1.21

kernel: add smsc95xx packetsize module param

kernel: config: Enabled IPV6_SUBTREES
See: raspberrypi/linux#1370

kernel: reboot: Use power off rather than busy spinning when halt is requested

firmware: arm_loader: Strip comments after dtoverlay and dtparam
See: http://forum.kodi.tv/showthread.php?tid=250817&pid=2298996#pid2298996

firmware: dtoverlay: Allow aliases to be used with target-path
firmware: dtoverlay: Support disabled (__dormant__) fragments
firmware: dtoverlay: Multiple overlay instances
firmware: host_applications: Add dtmerge application
See: https://www.raspberrypi.org/forums/viewtopic.php?f=107&t=139732

firmware: clock: Make clock logging less spammy. Can be enabled by host

firmware: config: Remove unsupported config options

firmware: Fix typos in comments
See: raspberrypi/userland#299

firmware: hello_video: Remove the timout, to avoid the application quits before the ending of some videos
See: #475

Author: popcornmix

boot/fixup.dat

@@ -344,6 +344,8 @@ Info:   Adds support for a number of I2C Real Time Clock devices
 Load:   dtoverlay=i2c-rtc,<param>=<val>
 Params: ds1307                  Select the DS1307 device
 
+        ds1339                  Select the DS1339 device
+
         ds3231                  Select the DS3231 device
 
         mcp7941x                Select the MCP7941x device
@@ -354,6 +356,8 @@ Params: ds1307                  Select the DS1307 device
 
         pcf8563                 Select the PCF8563 device
 
+        trickle-resistor-ohms   Resistor value for trickle charge (DS1339-only)
+
 
 Name:   i2c0-bcm2708
 Info:   Enable the i2c_bcm2708 driver for the i2c0 bus