arm64: configs: Remove SYS_BOOTM_LEN for TI devices

AM62x BOOTM_LEN is too small to contain OS images. Removing this sets the
size to a default 0x4000000 (for all arm64 devices).

It is unnecessary to specifically call the default size for the other
configs.

Signed-off-by: Kamlesh Gurudasani <kamlesh@ti.com>
Signed-off-by: Aashvij Shenai <a-shenai@ti.com>
7 files changed