mailbox: mtk-cmdq: Fix CURR and END addr for task insert case

mailbox: mtk-cmdq: Fix CURR and END addr for task insert case

Fix CURR and END address calculation for inserting a cmdq task into the
task list by using cmdq_reg_shift_addr() for proper address converting.
This ensures both CURR and END addresses are set correctly when
enabling the thread.

Fixes: a195c7ccfb7a ("mailbox: mtk-cmdq: Refine DMA address handling for the command buffer")
Signed-off-by: Jason-JH Lin <jason-jh.lin@mediatek.com>
Signed-off-by: Jassi Brar <jassisinghbrar@gmail.com>