The jz code can do several useful things like dumping the IPL and SPL.
The Fiio code can play with backlight and has code do dump the IPL
and SPL with the correct parameters (extracted by reverse engineering).
Change-Id: I317b3174f5db8d38c9a56670c1d45565142ec208
Also use this opportunity to cleanup support for multiple devices: the shell
now supports dynamic changes in the device and will call init() everytime
a new device is selected, to prepare a new environment. The shell now
honors register width on register read/write. The shell also provides access
to variants as follows by creating a subtable under the register using the
variant type in UPPER case and having the same layout as a register.
For example if register HW.GPIO.DIR has variants "set" and "clr", those can
be used like this:
HW.GPIO.DIR.SET.write(0xff)
HW.GPIO.DIR.CLR.write(0xff00)
Change-Id: I943947fa98bce875de0cba4338e8b7196a4c1165
