OMAP3 clock: Remove FreqSel for 3630

DPLL_FREQSEL field in CLKEN_PLL register is no longer valid for
OMAP3630. So remove references to that.

Signed-off-by: Vishwanath BS <vishwanath.bs@ti.com>
Cc: Sergei Shtylyov <sshtylyov@mvista.com>
[paul@pwsan.com: added comment fix from Sergei Shtylyov]
Signed-off-by: Paul Walmsley <paul@pwsan.com>