net/mlxfw: Fix out-of-memory error in mfa2 flash burning

The burning process requires to perform internal allocations of large
chunks of memory. This memory doesn't need to be contiguous and can be
safely allocated by vzalloc() instead of kzalloc(). This patch changes
such allocation to avoid possible out-of-memory failure.

Fixes: 410ed13c ("Add the mlxfw module for Mellanox firmware flash process")
Signed-off-by: Vladyslav Tarasiuk <vladyslavt@mellanox.com>
Reviewed-by: Aya Levin <ayal@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Tested-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>