remoteproc: qcom: q6v5: Fix NULL vs IS_ERR() bug in q6v5_alloc_memory_region()

remoteproc: qcom: q6v5: Fix NULL vs IS_ERR() bug in q6v5_alloc_memory_region()

The devm_ioremap_resource_wc() function never returns NULL, it returns
error pointers.  Update the checking to match.

Fixes: c70b9d5fdcd7 ("remoteproc: qcom: Use of_reserved_mem_region_* functions for "memory-region"")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Link: https://lore.kernel.org/r/674b32a78563282adeaf3cdf941314a0b8181026.1764427595.git.dan.carpenter@linaro.org
Signed-off-by: Bjorn Andersson <andersson@kernel.org>