gadget: f_fastboot: New Kconfig option USB_GADGET_FASTBOOT_CMD_OEM ...

Most fastboot commands are suitable for a secure boot environment as
they only allow to download/flash/erase to files/partitions which were
explicitly specified in the usbgadget command.

The "oem" group of commands allows execution of arbitrary barebox
commands. This needs to be disabled for secure boot devices.

Signed-off-by: Christian Eggers <ceggers@arri.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: i.MX: extend kindle-mx50 defconfig ...

The current defaultenv-kindle-mx50 requires MCI_STARTUP to boot the installed
linux. CMD_LOADY is mentioned in the doc for barebox update purposes.
FS_EXT4, FS_FAT and FS_FAT_WRITE gives users file system access. Also enable
CMD_MEMTEST, CMD_CLK, CMD_REGULATOR and CMD_EDIT for interested users.
The extended image will consume 195kB of available 253kB.

Signed-off-by: Alexander Kurz <akurz@blala.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

ARM: i.MX: add defconfig for the Kindle i.MX50 boards ...

Pin down the minimal config needed for a Kindle 4/5 device to boot into
the vendor Linux.

As the board documentation says, there is an upper limit of ~240 KB for
the bootloader partition on those devices. Using XZ image compression
instead of the default LZO reduced the file size from 214 KB to 172 KB,
so enabling that too.

Signed-off-by: Roland Hieber <rohieb@rohieb.name>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>