This patch changes 24xx to use new register access, except for clock
framework. Clock framework register access will get updates in the
next patch.

Note that board-*.c files change GPMC (General Purpose Memory Controller)
access to use gpmc_cs_write_reg() instead of accessing the registers
directly. The code also uses gpmc_fck instead of it's parent clock
core_l3_ck for GPMC clock.

The H4 board file also adds h4_init_flash() function, which specify the
flash start and end addresses.

Also note that sleep.S removes some unused registers addresses.
Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>