mmio: add 16-bit variants of read/write/set

Change-Id: If4fb5585865768daa151bd4aa343ac5c84d2e9c3
i2c: general clean-up

Implement changes based on Kees comments on the code review:
	http://gerrit-minix.few.vu.nl/#/c/676/

Changes:
 - use spin API instead of micro_delay() for busy-wait loops.
 - use read16/write16/set16 from mmio.h to access I2C registers.
 - reduce the timeout for soft reset.
 - in read/write, don't mix variable declaration and initialization.
 - after transfer, wait for access ready instead of blindly delaying.
 - rename constants am335x, dm37xx to AM335X_I2C_BUS, DM37XX_I2C_BUS.
 - rename ADDRESS_MASK to MAX_I2C_SA_MASK for clairity.
 - rename omap_i2c_claim_bus() to omap_i2c_bus_is_free().

Change-Id: Ic221e6134e024ea0a6690f21cff208a728286948
mined: K&R to ANSI, fix function sigs & warnings

 - Re-write function declarations from K&R style to ANSI style.
 - Change declaration of write_char(), S(), in_list() to match ptotos.
 - Resolve clang warnings about assignments in conditionals.

Change-Id: I61624b18afbefe1ff29941233d274bd6c0f12520
loadramdisk: bug fix for bad fprintf() format

An fprintf() has two %s formats but only one additional argument.

Include the name of the device file in the fprintf() call to
balance the arguments and format.

Change-Id: I62e702cf0bc9935897c2f85b0acc3b62b41d654a