configs: am64x_evm_r5_defconfig: Fix CONFIG_SPL_TEXT_BASE to 0x70000000

configs: am64x_evm_r5_defconfig: Fix CONFIG_SPL_TEXT_BASE to 0x70000000

CONFIG_SPL_TEXT_BASE was set to 0x70000000 in the commit,
"26f32c32b250 configs: am64x_evm_*_defconfig: Rearrange the components in
SRAM to satisfy the limitations for USB DFU boot mode". This change seems
to have been dropped during a merge commit.

Therefore, fix this by setting CONFIG_SPL_TEXT_BASE to 0x70000000.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Signed-off-by: Lokesh Vutla <lokeshvutla@ti.com>
Link: https://lore.kernel.org/r/20210726145840.18977-1-a-govindraju@ti.com