net: ti: icssg-prueth: Read firmware-names from device tree

net: ti: icssg-prueth: Read firmware-names from device tree

Refactor the way firmware names are handled for the ICSSG PRUETH driver.
Instead of using hardcoded firmware name arrays for different modes (EMAC,
SWITCH, HSR), the driver now reads the firmware names from the device tree
property "firmware-name". Only the EMAC firmware names are specified in the
device tree property. The firmware names for all other supported modes are
generated dynamically based on the EMAC firmware names by replacing
substrings (e.g., "eth" with "sw" or "hsr") as appropriate.

Example: Below are the firmwares used currently for PRU0 core

EMAC: ti-pruss/am65x-sr2-pru0-prueth-fw.elf
SW  : ti-pruss/am65x-sr2-pru0-prusw-fw.elf
HSR : ti-pruss/am65x-sr2-pru0-pruhsr-fw.elf

All three firmware names are same except for the operating mode.

In general for PRU0 core, firmware name is,

        ti-pruss/am65x-sr2-pru0-pru<mode>-fw.elf

Since the EMAC firmware names are defined in DT, driver will read those
directly and for other modes swap the mode name. i.e. eth -> sw or
eth -> hsr.

This preserves backwards compatibility as ICSSG driver is supported only
by AM65x and AM64x. Both of these have "firmware-name" property
populated in their device tree.

Signed-off-by: MD Danish Anwar <danishanwar@ti.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250613064547.44394-1-danishanwar@ti.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>