rtase: Fix a check for error in rtase_alloc_msix()

rtase: Fix a check for error in rtase_alloc_msix()

The pci_irq_vector() function never returns zero.  It returns negative
error codes or a positive non-zero IRQ number.  Fix the error checking to
test for negatives.

Fixes: a36e9f5cfe9e ("rtase: Add support for a pci table in this module")
Signed-off-by: Dan Carpenter <dan.carpenter@linaro.org>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Link: https://patch.msgid.link/f2ecc88d-af13-4651-9820-7cc665230019@stanley.mountain
Signed-off-by: Jakub Kicinski <kuba@kernel.org>