i2c: designware: Initialize adapter name only when not set

Check if the adapter name is already set in the driver prior to
initializing with generic name in i2c_dw_probe_master(). This
check allows to retain the unique adapter name driver has
initialized, which platform driver can use to distinguish it
from other i2c designware adapters.

Tested-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Pratap Nirujogi <pratap.nirujogi@amd.com>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>
Link: https://lore.kernel.org/r/20250609155601.1477055-2-pratap.nirujogi@amd.com