board: mpfs_icicle: fix pointer assignment in board_fdt_blob_setup()

board: mpfs_icicle: fix pointer assignment in board_fdt_blob_setup()

Correct the assignment in board_fdt_blob_setup() to use *fdtp instead of
fdtp, ensuring the caller receives the correct FDT address. This
resolves an issue where the device tree pointer was not properly set due
to assigning to the local parameter rather than the dereferenced
pointer.

Fixes: 7c16ebba1ed ("board: mpfs_icicle: implement board_fdt_blob_setup()/board_fit_config_name_match()")
Signed-off-by: Jamie Gibbons <jamie.gibbons@microchip.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>