SignedCapsulePkg SystemCapsuleLib: Change some dbg level to DEBUG_INFO

SignedCapsulePkg SystemCapsuleLib: Change some dbg level to DEBUG_INFO

This debug message should be info instead of error. This patch is to
change the debug level to DEBUG_INFO.
DEBUG((DEBUG_ERROR, "checking FV....0x%08x - 0x%x\n",
       FvHeader, FvHeader->FvLength));    // "Mark"

This comment is inaccurate. This patch is to remove it.
//
// Check section
//

This debug message should be removed as FvHeader may have been out of
range FdStart and FdSize, and the loop will go to "Mark" above again if
FvHeader is not out of range FdStart and FdSize, and then that debug
message will be shown. This patch is to remove this debug message.
DEBUG((DEBUG_ERROR, "Next FV....0x%08x - 0x%x\n",
       FvHeader, FvHeader->FvLength));

Cc: Jiewen Yao <jiewen.yao@intel.com>
Cc: Chasel Chiu <chasel.chiu@intel.com>
Cc: Amy Chan <amy.chan@intel.com>
Cc: Rangasai V Chaganty <rangasai.v.chaganty@intel.com>
Contributed-under: TianoCore Contribution Agreement 1.1
Signed-off-by: Star Zeng <star.zeng@intel.com>
Reviewed-by: Chasel Chiu <chasel.chiu@intel.com>
Reviewed-by: Jiewen Yao <jiewen.yao@intel.com>