nvme: Split out PCI support

Apple SoCs have an integrated NVMe controller that isn't connected
over a PCIe bus. In preparation for adding support for this NVMe
controller, split out the PCI support into its own file. This file
is selected through a new CONFIG_NVME_PCI Kconfig option, so do
a wholesale replacement of CONFIG_NVME with CONFIG_NVME_PCI.

Signed-off-by: Mark Kettenis <kettenis@openbsd.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested on: Macbook Air M1
Tested-by: Simon Glass <sjg@chromium.org>
diff --git a/configs/qemu-x86_defconfig b/configs/qemu-x86_defconfig
index b0cf701..928fa68 100644
--- a/configs/qemu-x86_defconfig
+++ b/configs/qemu-x86_defconfig
@@ -43,7 +43,7 @@
 CONFIG_SYS_ATA_ALT_OFFSET=0
 CONFIG_ATAPI=y
 CONFIG_CPU=y
-CONFIG_NVME=y
+CONFIG_NVME_PCI=y
 CONFIG_SPI=y
 CONFIG_USB_KEYBOARD=y
 CONFIG_FRAMEBUFFER_SET_VESA_MODE=y