net/fungible: Fix reference to __udivdi3 on 32b builds

net/fungible: Fix reference to __udivdi3 on 32b builds

32b builds with CONFIG_PHYS_ADDR_T_64BIT=y, such as i386 PAE,
raise a linker error due to a 64b division:

ld: drivers/net/ethernet/fungible/funcore/fun_dev.o: in function
`fun_dev_enable':
(.text+0xe1a): undefined reference to `__udivdi3'

The divisor in the offendinng expression is a power of 2. Change it to
use an explicit right shift.

Fixes: e1ffcc66818f ("net/fungible: Add service module for Fungible drivers")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Dimitris Michailidis <dmichail@fungible.com>
Link: https://lore.kernel.org/r/20220401232411.313881-1-dmichail@fungible.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>