omap-common/omap4: relocate early UART clock setup

omap-common/omap4: relocate early UART clock setup

Moves the early UART clock setup setup_clocks_for_console() from
preloader_console_init() to s_init() of OMAP4.

This is done to prepare for OMAP3 integration.

This patch was posted seperatly to the mailinglist but I decidet - since it is
a prereqesit for this patch to add it. Former port to ML:
http://article.gmane.org/gmane.comp.boot-loaders.u-boot/104395

Signed-off-by: Simon Schwarz <simonschwarzcor@gmail.com>
Signed-off-by: Tom Rini <trini@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>