efi: forward declare 'struct semaphore'

We don't need to include thread.h because struct semaphore is never
actually used in the EFI code.

Fixes,

efi/main.c:171:26: warning: ‘struct semaphore’ declared inside parameter list [enabled by default]
efi/main.c:171:26: warning: its scope is only this definition or declaration, which is probably not what you want [enabled by default]

Signed-off-by: Matt Fleming <matt.fleming@intel.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/efi/main.c b/efi/main.c
index 19f8b388..e6095fc9 100644
--- a/efi/main.c
+++ b/efi/main.c
@@ -168,6 +168,7 @@ void pxe_int1a(void)
 
 uint8_t KeepPXE;
 
+struct semaphore;
 mstime_t sem_down(struct semaphore *sem, mstime_t time)
 {
 	/* EFI is single threaded */