eeprom93xx: fix coding style

scripts/checkpatch.pl reports about some style problems,
this commit fixes some of them:

ERROR: space prohibited before open square bracket '['
+    .fields      = (VMStateField []) {

ERROR: space prohibited after that '!' (ctx:BxW)
+    if (! eeprom->eecs && eecs) {
         ^

ERROR: space prohibited after that '!' (ctx:WxW)
+    } else if (eeprom->eecs && ! eecs) {
                                ^

ERROR: space prohibited after that '!' (ctx:WxW)
+    } else if (eecs && ! eeprom->eesk && eesk) {
                        ^

ERROR: switch and case should be at the same indent
                     switch (address >> (eeprom->addrbits - 2)) {
+                        case 0:
[...]
+                        case 1:
[...]
+                        case 2:
[...]
+                        case 3:

ERROR: return is not a function, parentheses are not required
+    return (eeprom->eedo);

ERROR: switch and case should be at the same indent
     switch (nwords) {
+        case 16:
+        case 64:
[...]
+        case 128:
+        case 256:
[...]
+        default:

Signed-off-by: Antony Pavlov <antonynpavlov@gmail.com>
Cc: Stefan Weil <sw@weilnetz.de>
Reviewed-by: Stefan Weil <sw@weilnetz.de>
Cc: qemu-trivial@nongnu.org
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
