configs: ti: armv7: Fixes bug in fit_loadaddr for ramfs boot

The load address of ramdisk, rdaddr is 0x88080000 and fit_loadaddr
is defined as 0x88000000. This leaves only 512Kbytes for the
fit image. When the FIT images are larger than this, it will
overwite the ramdisk and cause the boot to fail.

For eg, The K2 HS fit images are a few MB and end up overwriting
the ramdsk. This patch moves the fit_loadaddr to 0x87000000,
leaving a 16MB window for the fit image. This memory can be
reclaimed once the kernel starts running.

Signed-off-by: Madan Srinivas <madans@ti.com>