net: ethernet: ti: am65-cpts: fix build

It's possible to have build configuration which will force PTP_1588_CLOCK=m
and so TI_K3_AM65_CPTS=m while still have TI_K3_AM65_CPSW_NUSS=y. This will
cause build failures:

aarch64-linux-gnu-ld: ../drivers/net/ethernet/ti/am65-cpsw-nuss.o: in function `am65_cpsw_init_cpts':
../drivers/net/ethernet/ti/am65-cpsw-nuss.c:1685: undefined reference to `am65_cpts_create'
aarch64-linux-gnu-ld: ../drivers/net/ethernet/ti/am65-cpsw-nuss.c:1685:(.text+0x2e20):
relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `am65_cpts_create'

Fix it by adding dependencies from CPTS in TI_K3_AM65_CPSW_NUSS as below:
   config TI_K3_AM65_CPSW_NUSS
   ...
     depends on TI_K3_AM65_CPTS || !TI_K3_AM65_CPTS

Note. This will create below dependencies and for NFS boot + CPTS all of them
have to be built-in.
  PTP_1588_CLOCK -> TI_K3_AM65_CPTS -> TI_K3_AM65_CPSW_NUSS

While here, clean up TI_K3_AM65_CPTS definition.

Fixes: b1f66a5b ("net: ethernet: ti: am65-cpsw-nuss: enable packet timestamping support")
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Reported-by: Anders Roxell <anders.roxell@linaro.org>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>