arm64: el2_setup.h: fix spelling typo in comments

- "evailable" -> "available"
Signed-off-by: Prathu Baronia <prathubaronia2011@gmail.com>
Reviewed-by: Mukesh Ojha <quic_mojha@quicinc.com>
Link: https://lore.kernel.org/r/20230123110639.10473-1-prathubaronia2011@gmail.comSigned-off-by: Catalin Marinas <catalin.marinas@arm.com>

arch/arm64/include/asm/el2_setup.h

@@ -177,7 +177,7 @@
 /**
  * Initialize EL2 registers to sane values. This should be called early on all
  * cores that were booted in EL2. Note that everything gets initialised as
- * if VHE was not evailable. The kernel context will be upgraded to VHE
+ * if VHE was not available. The kernel context will be upgraded to VHE
  * if possible later on in the boot process
  *
  * Regs: x0, x1 and x2 are clobbered.