fpga: altera-cvp: Avoid out-of-bounds read in trailing byte write

In the Linux kernel, the following vulnerability has been resolved: fpga: altera-cvp: Avoid out-of-bounds read in trailing byte write The trailing byte path in altera_cvp_send_block() dereferences a u32 pointer even when only 1-3 bytes remain in the input buffer. If the buffer ends at a page or scatterlist boundary, this can read past the valid image data and fault. Copy the remaining bytes into a zero-initialized u32 before writing the final word so only valid bytes are read from the input buffer.