MX28: Drop the cp15 reconfiguration from SPL

MX28: Drop the cp15 reconfiguration from SPL

The SPL doesn't need the CP15 reconfiguration, as that's what the
BootROM does for us already. Moreover, when the CP15 is reconfigured
and the code returns control to BootROM, the USB boot works no more.

Remove the code and allow [1] to work properly as well.

[1] http://git.bfuser.eu/?p=marex/mxsldr.git;a=summary

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Stefano Babic <sbabic@denx.de>