drivers: pcie: Do not enable PCIe RC module shell for endpoint

PCIe shell was enabled by default if shell is enabled in below commit:
commit ee985d81 ("shell: enable modules by default if shell is
enabled").

However, this shell file has tests for PCIe RC, not applicable to EP.
So, should not be default enabled for PCIe EP.

If we add EP shell tests in future, they should be added under
drivers/pcie/endpoint/ directory.

Signed-off-by: Abhishek Shah <abhishek.shah@broadcom.com>