RDMA/mana_ib: Ensure variable err is initialized

In the function mana_ib_gd_create_dma_region if there are no dma blocks
to process the variable `err` remains uninitialized.

Fixes: 0266a177 ("RDMA/mana_ib: Add a driver for Microsoft Azure Network Adapter")
Signed-off-by: Kees Bakker <kees@ijzerbout.nl>
Link: https://patch.msgid.link/20250221195833.7516C16290A@bout3.ijzerbout.nl


Reviewed-by: Long Li <longli@microsoft.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>