ARM: OMAP2+: clkt2xxx_apll.c: Remove some unused functions

Removes some functions that are not used anywhere:
omap2_clk_apll54_disable() omap2_clk_apll96_disable()
omap2_clk_apll54_enable() omap2_clk_apll96_enable() omap2xxx_get_apll_clkin()
omap2_clk_apll96_recalc() omap2_clk_apll54_recalc()

This was partially found by using a static code analysis program called cppcheck.

Signed-off-by: Rickard Strandqvist <rickard_strandqvist@spectrumdigital.se>
[tony@atomide.com: updated to fix a build warning]
Signed-off-by: Tony Lindgren <tony@atomide.com>