trusty: Cast SMC numbers and errors to 32-bit The SMC function ID and error code are returned in w0 and w2 even on AArch64, so cast the 64-bit values we have from the registers to 32 bits explicitly. Bug: 283822781 Change-Id: I90357d063078f245190f946363f1a3e90724178e Signed-off-by: Andrei Homescu <[email protected]>