dpll: zl3073x: Fix double free in zl3073x_devlink_flash_update()

dpll: zl3073x: Fix double free in zl3073x_devlink_flash_update()

The zl3073x_devlink_flash_prepare() function calls zl3073x_fw_free() and
the caller, zl3073x_devlink_flash_update(), also calls that same free
function so it leads to a double free.  Delete the extra free.

Fixes: a1e891fe4ae8 ("dpll: zl3073x: Implement devlink flash callback")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Ivan Vecera <ivecera@redhat.com>
Reviewed-by: Vadim Fedorenko <vadim.fedorenko@linux.dev>
Link: https://patch.msgid.link/aNVDbcIQq4RmU_fl@stanley.mountain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>