Update to android-mainline kernel headers v5.4.

Update generate_uapi_headers.sh to checkout the android mainline
kernel. Also, add a small modification to look for the kernel directory
in common not linux-stable.

Remove deprecated android headers from android/uapi/linux. Also,
remove f_accessory.h since it's in the android mainline kernel.

Test: Builds and runs on walleye.
Change-Id: Ia371305e19f56e6bcc2db6d5b4d299819f07ffc6
diff --git a/libc/kernel/uapi/asm-arm64/asm/kvm.h b/libc/kernel/uapi/asm-arm64/asm/kvm.h
index e345744..1c7ee65 100644
--- a/libc/kernel/uapi/asm-arm64/asm/kvm.h
+++ b/libc/kernel/uapi/asm-arm64/asm/kvm.h
@@ -196,8 +196,10 @@
 #define KVM_ARM_VCPU_TIMER_CTRL 1
 #define KVM_ARM_VCPU_TIMER_IRQ_VTIMER 0
 #define KVM_ARM_VCPU_TIMER_IRQ_PTIMER 1
+#define KVM_ARM_IRQ_VCPU2_SHIFT 28
+#define KVM_ARM_IRQ_VCPU2_MASK 0xf
 #define KVM_ARM_IRQ_TYPE_SHIFT 24
-#define KVM_ARM_IRQ_TYPE_MASK 0xff
+#define KVM_ARM_IRQ_TYPE_MASK 0xf
 #define KVM_ARM_IRQ_VCPU_SHIFT 16
 #define KVM_ARM_IRQ_VCPU_MASK 0xff
 #define KVM_ARM_IRQ_NUM_SHIFT 0