arm: configs: imote2: Drop defconfig as board support dropped.

Missed the defconfig when removing the board files causing
failures in builds using this defconfig.

Fixes: 28f74201

 ("ARM: pxa: remove Intel Imote2 and Stargate 2 boards")
Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20220405135252.10283-1-Jonathan.Cameron@huawei.com'
Signed-off-by: Arnd Bergmann <arnd@arndb.de>