flash_fp_mcu: Add delay to consider bootloader startup
flash_fp_mcu: Add delay to consider bootloader startup

Add delay of 100 ms to consider minimum bootloader start time for stm32.
This fix prevents triggering stm32mon before bootloader is finished.

BRANCH=none
BUG=b:185074067
TEST=Multiple 'flash_fp_mcu <fpfw>'
     Tested on coachz, nocturne and morphius boards

Change-Id: Ic60e9e67c29664ce22bfc66bec6eaf76ffc80454
Signed-off-by: Sujit Kautkar <f9f7a7404b5ff25066897d3057e046ccff113ee1@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2837485
Tested-by: Sujit Kautkar <f9f7a7404b5ff25066897d3057e046ccff113ee1@chromium.org>
Reviewed-by: Alexandru M Stan <1784cbba6d7675b1eba55eaefe41c7672ad9da3b@chromium.org>
Commit-Queue: Sujit Kautkar <f9f7a7404b5ff25066897d3057e046ccff113ee1@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec