Partially Revert "flash/stm32l4x: introduce flash programming without loader"

Partially Revert "flash/stm32l4x: introduce flash programming without loader"

This partially reverts commit 1247eee4e6e5.

There is no reasonable use cases where work-area should be enabled
and working, and it can't be used for the flash loader.

Instead of introducing driver specific property, users can disable
flash load by disabling work-area, for example by setting it to 0.

But still we keep the function stm32l4_write_block_without_loader
to be used when workarea is not available (no sufficient size or zero)

Change-Id: Ibb046c74df354c6067bac978e8ef7efb47d9fd2b
Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
Signed-off-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6569
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Tested-by: jenkins