ARM: OMAP2+: Remove the unneeded result variable

Return the value amx3_common_init() directly instead of storing it in
another redundant variable.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: ye xingchen <ye.xingchen@zte.com.cn>
Message-Id: <20220920065113.215685-1-ye.xingchen@zte.com.cn>
Signed-off-by: Tony Lindgren <tony@atomide.com>