habanalabs: fix PCIe access to SRAM via debugfs

hl_access_sram_dram_region() uses a region base which is set within the
hl_set_dram_bar() function. However, for SRAM access this function is
not called, and we end up with a wrong value of region base and with a
bad calculated address.
Fix it by initializing the region base value independently of whether
hl_set_dram_bar() is called or not.

Signed-off-by: Tomer Tayar <ttayar@habana.ai>
Reviewed-by: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>