board: ti: am57xx: Remove "ti/omap/" from name_fit_config

board: ti: am57xx: Remove "ti/omap/" from name_fit_config

Commit 649f4a7d3ca7 ("board: ti: am57xx: Set fdtfile from C code
instead of findfdt script") prepends "ti/omap/" to the actual name
of the fdtfile whereas fit image boot needs exact dtb name. So, remove
"ti/omap" from name_fit_config by substituting it with an empty string.

Fixes: 649f4a7d3ca7 ("board: ti: am57xx: Set fdtfile from C code instead of findfdt script")
Signed-off-by: Anurag Dutta <a-dutta@ti.com>
Reviewed-by: Udit Kumar <u-kumar1@ti.com>