net: airoha: Fix FE_PSE_BUF_SET configuration if PPE2 is available

net: airoha: Fix FE_PSE_BUF_SET configuration if PPE2 is available

airoha_fe_set routine is used to set specified bits to 1 in the selected
register. In the FE_PSE_BUF_SET case this can due to a overestimation of
the required buffers for I/O queues since we can miss to set some bits
of PSE_ALLRSV_MASK subfield to 0. Fix the issue relying on airoha_fe_rmw
routine instead.

Fixes: 8e38e08f2c560 ("net: airoha: fix PSE memory configuration in airoha_fe_pse_ports_init()")
Tested-by: Xuegang Lu <xuegang.lu@airoha.com>
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Link: https://patch.msgid.link/20260408-airoha-reg_fe_pse_buf_set-v1-1-0c4fa8f4d1d9@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>