KVM: Documentation: Fix typo `BFD`

BDF is the acronym for Bus, Device, Function.
Signed-off-by: Changyuan Lyu <changyuanl@google.com>
Link: https://lore.kernel.org/r/20240623164542.2999626-1-changyuanl@google.comSigned-off-by: Oliver Upton <oliver.upton@linux.dev>

Documentation/virt/kvm/api.rst

@@ -1921,7 +1921,7 @@ flags:
 
 If KVM_MSI_VALID_DEVID is set, devid contains a unique device identifier
 for the device that wrote the MSI message.  For PCI, this is usually a
-BFD identifier in the lower 16 bits.
+BDF identifier in the lower 16 bits.
 
 On x86, address_hi is ignored unless the KVM_X2APIC_API_USE_32BIT_IDS
 feature of KVM_CAP_X2APIC_API capability is enabled.  If it is enabled,
@@ -2986,7 +2986,7 @@ flags:
 
 If KVM_MSI_VALID_DEVID is set, devid contains a unique device identifier
 for the device that wrote the MSI message.  For PCI, this is usually a
-BFD identifier in the lower 16 bits.
+BDF identifier in the lower 16 bits.
 
 On x86, address_hi is ignored unless the KVM_X2APIC_API_USE_32BIT_IDS
 feature of KVM_CAP_X2APIC_API capability is enabled.  If it is enabled,