ARM: OMAP1: Update dpll1 default rate reprogramming method

According to comments in omap1_select_table_rate(), reprogramming dpll1
is tricky, and should always be done from SRAM.

While being at it, move OMAP730 special case handling inside
omap_sram_reprogram_clock().

Created on top of version 2 of the series "ARM: OMAP1: Fix dpll1
reprogramming related issues", which it depends on.
Tested on Amstrad Delta.

Signed-off-by: Janusz Krzysztofik <jkrzyszt@tis.icnet.pl>
Signed-off-by: Tony Lindgren <tony@atomide.com>