lib: Allow for the DIM library to be modular

Allow the Dynamic Interrupt Moderation (DIM) library to be built as a
module. This is particularly useful in an Android GKI (Google Kernel
Image) configuration where everything is built as a module, including
Ethernet controller drivers. Having to build DIMLIB into the kernel
image with potentially no user is wasteful.

Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Alexander Lobakin <aleksander.lobakin@intel.com>
Link: https://lore.kernel.org/r/20240506175040.410446-1-florian.fainelli@broadcom.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>