nvidia-peermem: Prefer ofa_kernel-dkms path for DOCA-OFED headers

Since DOCA 3.2.0, DKMS is the default OFED drivers' installation
method. These store the headers in /usr/src/ofa_kernel-dkms/ and
create symlinks from /usr/src/ofa_kernel/ for backward
compatibility.

Using the -dkms path directly is more robust as it contains the
actual files, avoiding potential issues with symlinks that may be
missing, broken, or not yet created during package installation.

Add ofa_kernel-dkms as the highest-priority candidate, drop the
/var/lib/dkms/mlnx-ofed-kernel/ fallback whose directory structure
never matched the expected layout, and replace the shell for-loop
with $(firstword $(wildcard ...)) to match the pattern used by
OFED's own DKMS submodules.

Signed-off-by: Leonid Bloch <lb.workbox@gmail.com>

Author: blochl

kernel-open/nvidia-peermem/nvidia-peermem.Kbuild

@@ -43,17 +43,11 @@ else
     OFA_ARCH := $(ARCH)
 endif
 OFA_DIR := /usr/src/ofa_kernel
-OFA_CANDIDATES = $(OFA_DIR)/$(OFA_ARCH)/$(KERNELRELEASE) $(OFA_DIR)/$(KERNELRELEASE) $(OFA_DIR)/default /var/lib/dkms/mlnx-ofed-kernel
-MLNX_OFED_KERNEL := $(shell for d in $(OFA_CANDIDATES); do \
-                              if [ -d "$$d" ]; then \
-                                echo "$$d"; \
-                                exit 0; \
-                              fi; \
-                            done; \
-                            echo $(OFA_DIR) \
-                     )
+OFA_DKMS_DIR := $(OFA_DIR)-dkms
+OFA_CANDIDATES = $(OFA_DKMS_DIR)/$(OFA_ARCH)/$(KERNELRELEASE) $(OFA_DIR)/$(OFA_ARCH)/$(KERNELRELEASE) $(OFA_DIR)/$(KERNELRELEASE) $(OFA_DIR)/default
+MLNX_OFED_KERNEL := $(firstword $(wildcard $(OFA_CANDIDATES)))
 
-ifneq ($(shell test -d $(MLNX_OFED_KERNEL) && echo "true" || echo "" ),)
+ifneq ($(MLNX_OFED_KERNEL),)
     NVIDIA_PEERMEM_CFLAGS += -I$(MLNX_OFED_KERNEL)/include -I$(MLNX_OFED_KERNEL)/include/rdma
     KBUILD_EXTRA_SYMBOLS := $(MLNX_OFED_KERNEL)/Module.symvers
 endif