net: phy: aquantia: rename aquantia.c to aquantia_main.c

Rename aquantia.c to aquantia_main.c to be prepared for adding new
functionality to separate source code files.

Signed-off-by: Heiner Kallweit <[e-mail]>
Reviewed-by: Florian Fainelli <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/phy/Makefile

···
 obj-y				+= $(sfp-obj-y) $(sfp-obj-m)
 
 obj-$(CONFIG_AMD_PHY)		+= amd.o
+aquantia-objs			+= aquantia_main.o
 obj-$(CONFIG_AQUANTIA_PHY)	+= aquantia.o
 obj-$(CONFIG_ASIX_PHY)		+= asix.o
 obj-$(CONFIG_AT803X_PHY)	+= at803x.o