efi: Explain OVMF acronym in OVMF_DEBUG_LOG help text

People not very intimate with EFI may not know the meaning of the OVMF
acronym. Write it in full, to help users with making good decisions
when configuring their kernels.

Fixes: f393a761763c5427 ("efi: add ovmf debug log driver")
Signed-off-by: Geert Uytterhoeven <[e-mail]>
Reviewed-by: Richard Lyu <[e-mail]>
Acked-by: Gerd Hoffmann <[e-mail]>
Signed-off-by: Ard Biesheuvel <[e-mail]>

drivers/firmware/efi/Kconfig

···
 	bool "Expose OVMF firmware debug log via sysfs"
 	depends on EFI
 	help
-	  Recent OVMF versions (edk2-stable202508 + newer) can write
-	  their debug log to a memory buffer.  This driver exposes the
-	  log content via sysfs (/sys/firmware/efi/ovmf_debug_log).
+	  Recent versions of the Open Virtual Machine Firmware
+	  (edk2-stable202508 + newer) can write their debug log to a memory
+	  buffer.  This driver exposes the log content via sysfs
+	  (/sys/firmware/efi/ovmf_debug_log).
 
 config UNACCEPTED_MEMORY
 	bool