debug: Remove dependency of unsetting X86_IAMCU for CONFIG_DEBUG_INFO.

CONFIG_DEBUG_INFO was disabled for IAMCU targets. As per Jira update forked
arch/code is gone. So it should not block enabling DEBUG_INFO for IAMCU.

Currently CONFIG_DEBUG_INFO depends on (x86 = y && !X86_IAMCU)
CONFIG_DEBUG_INFO can not be set for IAMCU. this patch removes dependency.

Jira: ZEP-601

Change-Id: Ib5635096f83f7b931c277b667a55c6d54f8e946a
Signed-off-by: Youvedeep Singh <youvedeep.singh@intel.com>