pd: Add protection to FMAP data so it is not removed by linker
pd: Add protection to FMAP data so it is not removed by linker

Most of the pd ECs have CONFIG_LTO enabled which turns on GCC
Link-Time Optimizations. Unless protected, this removes the
FMAP data from the generated EC images.

BUG=chrome-os-partner:46442
TEST=Manually tested pd programming on Kunimitsu.
         flashrom -p ec:dev=1 -w ec.bin is successful
BRANCH=none

Change-Id: I3badd1b245ab7490d75331be8074a0557f7b4d4b
Signed-off-by: Shamile Khan <0b4042e69ed1abbbdd05548f229cef643986e254@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/310879
Reviewed-by: Shawn N <5259333ce42e3ace6a73988cec7115ed9d3a661a@chromium.org>

coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,akappy7/ChromeOS_EC_LED_Diagnostics,coreboot/chrome-ec,coreboot/chrome-ec