stmmac: dwmac-intel-plat: fix call balance of tx_clk handling routines

If the clock dwmac->tx_clk was not enabled in intel_eth_plat_probe,
it should not be disabled in any path.

Conversely, if it was enabled in intel_eth_plat_probe, it must be disabled
in all error paths to ensure proper cleanup.

Found by Linux Verification Center (linuxtesting.org) with Klever.

Fixes: 9efc9b2b ("net: stmmac: Add dwmac-intel-plat for GBE driver")
Signed-off-by: Vitalii Mordan <mordan@ispras.ru>
Link: https://patch.msgid.link/20241108173334.2973603-1-mordan@ispras.ru


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