atl1c: remove redundant assignment to variable size

Variable sie is being assigned a value that is never read. The
The assignment is redundant and can be removed.

Cleans up clang scan build warning:
drivers/net/ethernet/atheros/atl1c/atl1c_main.c:1054:22: warning:
Although the value stored to 'size' is used in the enclosing
expression, the value is never actually read from 'size'
[deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Link: https://lore.kernel.org/r/20220318005021.82073-1-colin.i.king@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>