Unset USE_BOOTCOMMAND for all ls1088 defconfig files to fix
redefinition error. USE_BOOTCOMMAND was introduced in commit
b6251db8c3 ("Kconfig: Introduce USE_BOOTCOMMAND and migrate
BOOTCOMMAND").
Signed-off-by: Ashish Kumar <Ashish.Kumar@nxp.com>
Reviewed-by: York Sun <york.sun@nxp.com>